Discussion:
Another design
(too old to reply)
Edward Rawde
2024-05-09 05:47:44 UTC
Permalink
Now with 9V to 15V input range, direct gate drive and 500mA LED current.

Startup behaviour is not ideal but maybe that can be fixed if it needs
fixing.

What's the cheapest op amp I can use for U2 instead of OP07?

Is there a cheaper comparator instead of LT1719 which will work?
Also the fet is bigger than it needs to ne.

Is there a better device for D4? Particularly if R4 can be reduced.

Will it work at all? Except in simulation.

Version 4
SHEET 1 2820 680
WIRE 1312 -272 0 -272
WIRE 1408 -208 288 -208
WIRE 976 -144 160 -144
WIRE 1088 -144 1040 -144
WIRE -32 -48 -64 -48
WIRE 0 -48 0 -272
WIRE 0 -48 -32 -48
WIRE 48 -48 0 -48
WIRE 240 -48 48 -48
WIRE 336 -48 240 -48
WIRE 448 -48 336 -48
WIRE 464 -48 448 -48
WIRE 528 -48 464 -48
WIRE 608 -48 528 -48
WIRE 672 -48 608 -48
WIRE 800 -48 768 -48
WIRE 816 -48 800 -48
WIRE 864 -48 816 -48
WIRE 992 -48 944 -48
WIRE 1024 -48 992 -48
WIRE 1136 -48 1024 -48
WIRE 240 -16 240 -48
WIRE 336 -16 336 -48
WIRE 1408 -16 1408 -208
WIRE 1136 0 1136 -48
WIRE -64 32 -64 -48
WIRE 448 64 448 -48
WIRE 464 64 464 -48
WIRE 48 80 48 -48
WIRE 160 80 160 -144
WIRE 240 80 240 64
WIRE 240 80 160 80
WIRE 336 80 336 64
WIRE 384 80 336 80
WIRE 416 80 384 80
WIRE 816 80 816 -48
WIRE 992 80 992 -48
WIRE 288 96 288 -208
WIRE 336 96 336 80
WIRE 336 96 288 96
WIRE 656 96 480 96
WIRE 688 96 688 0
WIRE 688 96 656 96
WIRE 240 112 240 80
WIRE 384 112 240 112
WIRE 416 112 384 112
WIRE 528 112 528 -48
WIRE 608 112 608 -48
WIRE 1088 112 1088 -144
WIRE 1136 112 1136 64
WIRE 1136 112 1088 112
WIRE 240 128 240 112
WIRE 336 128 336 96
WIRE -64 176 -64 112
WIRE 1312 192 1312 -272
WIRE 1136 208 1136 112
WIRE 1200 208 1136 208
WIRE 1280 208 1200 208
WIRE 1392 224 1344 224
WIRE 1408 224 1408 64
WIRE 1408 224 1392 224
WIRE 240 240 240 208
WIRE 336 240 336 208
WIRE 336 240 240 240
WIRE 432 240 432 128
WIRE 432 240 336 240
WIRE 448 240 448 128
WIRE 448 240 432 240
WIRE 464 240 464 128
WIRE 464 240 448 240
WIRE 528 240 528 176
WIRE 528 240 464 240
WIRE 608 240 608 176
WIRE 608 240 528 240
WIRE 640 240 608 240
WIRE 752 240 720 240
WIRE 1184 240 752 240
WIRE 1280 240 1184 240
WIRE 1136 256 1136 208
WIRE 752 272 752 240
WIRE -64 368 -64 256
WIRE 48 368 48 144
WIRE 48 368 -64 368
WIRE 752 368 752 336
WIRE 752 368 48 368
WIRE 816 368 816 144
WIRE 816 368 752 368
WIRE 992 368 992 144
WIRE 992 368 816 368
WIRE 1136 368 1136 336
WIRE 1136 368 992 368
WIRE 1312 368 1312 256
WIRE 1312 368 1136 368
WIRE -64 384 -64 368
FLAG -64 384 0
FLAG -32 -48 in
FLAG 800 -48 sw
FLAG 1024 -48 led
FLAG 1200 208 isense
FLAG 1184 240 iref
FLAG 1392 224 ifb
FLAG 384 80 cmp-
FLAG 384 112 cmp+
FLAG 656 96 gate
SYMBOL Comparators\\LT1719 448 32 R0
WINDOW 0 27 27 Left 2
WINDOW 3 -92 6 Left 2
SYMATTR InstName U1
SYMBOL res 320 112 R0
WINDOW 0 41 34 Left 2
WINDOW 3 35 64 Left 2
SYMATTR InstName R2
SYMATTR Value 10K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL ind 960 -64 R90
WINDOW 0 63 51 VBottom 2
WINDOW 3 -27 53 VTop 2
SYMATTR InstName L1
SYMATTR Value 100µ
SYMATTR SpiceLine Ipk=1.3 Rser=0.15 Rpar=0 Cpar=0
SYMBOL res 1120 240 R0
WINDOW 0 40 39 Left 2
WINDOW 3 39 70 Left 2
SYMATTR InstName R4
SYMATTR Value 1.5
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL res 224 -32 R0
WINDOW 0 -35 19 Left 2
WINDOW 3 -45 46 Left 2
SYMATTR InstName R3
SYMATTR Value 10K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL schottky 832 144 R180
WINDOW 0 -45 30 Left 2
WINDOW 3 -127 -3 Left 2
SYMATTR InstName D2
SYMATTR Value MBRS130L
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL pmos 768 0 M270
WINDOW 0 25 128 VLeft 2
WINDOW 3 69 92 VLeft 2
SYMATTR InstName M1
SYMATTR Value AO6407
SYMBOL voltage -64 160 R0
WINDOW 0 11 100 Left 2
WINDOW 3 38 54 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 -185 81 Left 2
SYMATTR InstName V3
SYMATTR Value 12
SYMBOL res -80 16 R0
SYMATTR InstName R8
SYMATTR Value 0.001
SYMBOL zener 544 176 R180
WINDOW 0 37 29 Left 2
WINDOW 3 68 -5 Right 2
SYMATTR InstName D1
SYMATTR Value UMZ5_1N
SYMBOL res 320 -32 R0
WINDOW 0 40 7 Left 2
WINDOW 3 37 33 Left 2
SYMATTR InstName R1
SYMATTR Value 10K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL res 736 224 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R6
SYMATTR Value 220
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL cap 592 176 M180
WINDOW 0 39 47 Left 2
WINDOW 3 37 16 Left 2
SYMATTR InstName C3
SYMATTR Value 0.1µ
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0.0337 Lser=180p
SYMBOL polcap 976 80 R0
WINDOW 3 24 56 Left 2
WINDOW 0 27 9 Left 2
SYMATTR Value 100µ
SYMATTR InstName C1
SYMATTR Description Capacitor
SYMATTR Type cap
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0.9 Lser=0
SYMBOL res 224 112 R0
WINDOW 0 -40 36 Left 2
WINDOW 3 -49 65 Left 2
SYMATTR InstName R5
SYMATTR Value 10K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL polcap 32 80 R0
WINDOW 3 24 56 Left 2
WINDOW 0 27 9 Left 2
SYMATTR Value 100µ
SYMATTR InstName C2
SYMATTR Description Capacitor
SYMATTR Type cap
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0.9 Lser=0
SYMBOL LED 1120 0 R0
SYMATTR InstName D3
SYMATTR Value LXZ1-PB01
SYMBOL res 1424 80 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R9
SYMATTR Value 22K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL cap 976 -160 M90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C5
SYMATTR Value 0.01µ
SYMATTR SpiceLine V=16 Irms=291m Rser=0.34258 Lser=0 mfg="KEMET"
pn="C0805F103K4RAC" type="X7R"
SYMBOL OpAmps\\OP07 1312 160 R0
SYMATTR InstName U2
SYMBOL diode 736 272 R0
WINDOW 0 -40 38 Left 2
WINDOW 3 -84 70 Left 2
SYMATTR InstName D4
SYMATTR Value 1N4148
TEXT -144 432 Left 2 !.tran 0.01 startup
Edward Rawde
2024-05-10 03:11:03 UTC
Permalink
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
Startup behaviour is not ideal but maybe that can be fixed if it needs
fixing.
What's the cheapest op amp I can use for U2 instead of OP07?
Is there a cheaper comparator instead of LT1719 which will work?
Also the fet is bigger than it needs to ne.
Is there a better device for D4? Particularly if R4 can be reduced.
Will it work at all? Except in simulation.
I think I've answered my own question for the current controller but I don't
think it's feasible to attempt a discrete comparator on cost grounds.

Version 4
SHEET 1 3044 680
WIRE 2032 -272 64 -272
WIRE 2192 -272 2032 -272
WIRE 2480 -272 2192 -272
WIRE 2192 -224 2192 -272
WIRE 2480 -224 2480 -272
WIRE 2336 -176 2256 -176
WIRE 2416 -176 2336 -176
WIRE 976 -128 160 -128
WIRE 1072 -128 1040 -128
WIRE 2032 -128 2032 -272
WIRE 2192 -80 2192 -128
WIRE 2336 -80 2336 -176
WIRE 2336 -80 2192 -80
WIRE 2480 -64 2480 -128
WIRE 2688 -64 2480 -64
WIRE 16 -48 -16 -48
WIRE 64 -48 64 -272
WIRE 64 -48 16 -48
WIRE 96 -48 64 -48
WIRE 240 -48 96 -48
WIRE 336 -48 240 -48
WIRE 448 -48 336 -48
WIRE 464 -48 448 -48
WIRE 528 -48 464 -48
WIRE 608 -48 528 -48
WIRE 672 -48 608 -48
WIRE 784 -48 768 -48
WIRE 816 -48 784 -48
WIRE 864 -48 816 -48
WIRE 992 -48 944 -48
WIRE 1024 -48 992 -48
WIRE 1072 -48 1072 -128
WIRE 1072 -48 1024 -48
WIRE 1264 -48 1072 -48
WIRE 1360 -48 1264 -48
WIRE 240 -16 240 -48
WIRE 336 -16 336 -48
WIRE 2192 -16 2192 -80
WIRE 2480 -16 2480 -64
WIRE 1264 0 1264 -48
WIRE 1360 0 1360 -48
WIRE -16 32 -16 -48
WIRE 2128 32 1872 32
WIRE 2592 32 2544 32
WIRE 448 64 448 -48
WIRE 464 64 464 -48
WIRE 96 80 96 -48
WIRE 160 80 160 -128
WIRE 240 80 240 64
WIRE 240 80 160 80
WIRE 336 80 336 64
WIRE 384 80 336 80
WIRE 416 80 384 80
WIRE 816 80 816 -48
WIRE 992 80 992 -48
WIRE 336 96 336 80
WIRE 336 96 288 96
WIRE 656 96 480 96
WIRE 688 96 688 0
WIRE 688 96 656 96
WIRE 1264 96 1264 64
WIRE 1312 96 1264 96
WIRE 1936 96 1312 96
WIRE 240 112 240 80
WIRE 384 112 240 112
WIRE 416 112 384 112
WIRE 528 112 528 -48
WIRE 608 112 608 -48
WIRE 240 128 240 112
WIRE 336 128 336 96
WIRE 1360 128 1360 80
WIRE 1424 128 1360 128
WIRE 1872 128 1872 32
WIRE 1872 128 1424 128
WIRE 2192 128 2192 80
WIRE 2352 128 2192 128
WIRE 2480 128 2480 80
WIRE 2480 128 2352 128
WIRE 2032 144 2032 -48
WIRE 2128 144 2032 144
WIRE 1360 160 1360 128
WIRE -16 176 -16 112
WIRE 2032 192 2032 144
WIRE 2352 192 2352 128
WIRE 240 240 240 208
WIRE 336 240 336 208
WIRE 336 240 240 240
WIRE 384 240 336 240
WIRE 432 240 432 128
WIRE 432 240 384 240
WIRE 448 240 448 128
WIRE 448 240 432 240
WIRE 464 240 464 128
WIRE 464 240 448 240
WIRE 528 240 528 176
WIRE 528 240 464 240
WIRE 544 240 528 240
WIRE 608 240 608 176
WIRE 608 240 544 240
WIRE 1360 240 1360 224
WIRE 1424 240 1360 240
WIRE 1536 240 1424 240
WIRE 1696 240 1600 240
WIRE 1872 240 1760 240
WIRE 2128 240 2128 144
WIRE 2128 240 2096 240
WIRE 2288 240 2128 240
WIRE 544 272 544 240
WIRE 1264 272 1264 96
WIRE 1360 272 1360 240
WIRE -16 368 -16 256
WIRE 96 368 96 144
WIRE 96 368 -16 368
WIRE 544 368 544 352
WIRE 544 368 96 368
WIRE 816 368 816 144
WIRE 816 368 544 368
WIRE 992 368 992 144
WIRE 992 368 816 368
WIRE 1264 368 1264 352
WIRE 1264 368 992 368
WIRE 1360 368 1360 336
WIRE 1360 368 1264 368
WIRE 1872 368 1872 240
WIRE 1872 368 1360 368
WIRE 2032 368 2032 288
WIRE 2032 368 1872 368
WIRE 2352 368 2352 288
WIRE 2352 368 2032 368
WIRE -16 384 -16 368
WIRE 1936 400 1936 96
WIRE 2592 400 2592 32
WIRE 2592 400 1936 400
WIRE 288 448 288 96
WIRE 992 448 288 448
WIRE 1328 448 1072 448
WIRE 2688 448 2688 -64
WIRE 2688 448 1328 448
FLAG -16 384 0
FLAG 16 -48 in
FLAG 784 -48 sw
FLAG 1024 -48 out
FLAG 1424 128 isense
FLAG 1312 96 iref
FLAG 1328 448 ifb
FLAG 384 80 cmp-
FLAG 384 112 cmp+
FLAG 656 96 gate
FLAG 384 240 cmpv-
FLAG 1424 240 led
SYMBOL Comparators\\LT1719 448 32 R0
WINDOW 0 27 27 Left 2
WINDOW 3 -92 6 Left 2
SYMATTR InstName U1
SYMBOL res 320 112 R0
WINDOW 0 41 34 Left 2
WINDOW 3 35 64 Left 2
SYMATTR InstName R4
SYMATTR Value 10K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL ind 960 -64 R90
WINDOW 0 63 51 VBottom 2
WINDOW 3 -27 53 VTop 2
SYMATTR InstName L1
SYMATTR Value 68µ
SYMATTR SpiceLine Ipk=0.85 Rser=0.21 Rpar=0 Cpar=0 mfg="Sumida"
pn="CDR105B-680"
SYMBOL res 1376 -16 M0
WINDOW 0 -37 34 Left 2
WINDOW 3 -57 63 Left 2
SYMATTR InstName R8
SYMATTR Value 0.68
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL res 224 -32 R0
WINDOW 0 -35 19 Left 2
WINDOW 3 -49 48 Left 2
SYMATTR InstName R1
SYMATTR Value 10K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL schottky 832 144 R180
WINDOW 0 -42 30 Left 2
WINDOW 3 -119 -3 Left 2
SYMATTR InstName D2
SYMATTR Value MBRS130L
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL pmos 768 0 M270
WINDOW 0 10 129 VLeft 2
WINDOW 3 -10 67 VLeft 2
SYMATTR InstName M1
SYMATTR Value AO6407
SYMBOL voltage -16 160 R0
WINDOW 0 -75 16 Left 2
WINDOW 3 -71 54 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 -185 81 Left 2
SYMATTR InstName V3
SYMATTR Value 12
SYMBOL res -32 16 R0
WINDOW 0 -39 29 Left 2
WINDOW 3 -63 65 Left 2
SYMATTR InstName R9
SYMATTR Value 0.001
SYMBOL zener 544 176 R180
WINDOW 0 37 29 Left 2
WINDOW 3 68 -5 Right 2
SYMATTR InstName D1
SYMATTR Value UMZ5_1N
SYMBOL res 320 -32 R0
WINDOW 0 40 7 Left 2
WINDOW 3 37 33 Left 2
SYMATTR InstName R3
SYMATTR Value 10K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL res 528 368 M180
WINDOW 0 39 76 Left 2
WINDOW 3 38 42 Left 2
SYMATTR InstName R5
SYMATTR Value 220
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL cap 592 176 M180
WINDOW 0 29 52 Left 2
WINDOW 3 30 13 Left 2
SYMATTR InstName C3
SYMATTR Value 0.1µ
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0.0337 Lser=180p
SYMBOL polcap 976 80 R0
WINDOW 3 24 56 Left 2
WINDOW 0 27 9 Left 2
SYMATTR Value 100µ
SYMATTR InstName C1
SYMATTR Description Capacitor
SYMATTR Type cap
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0.9 Lser=0
SYMBOL res 224 112 R0
WINDOW 0 -40 33 Left 2
WINDOW 3 -52 57 Left 2
SYMATTR InstName R2
SYMATTR Value 10K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL polcap 80 80 R0
WINDOW 3 -57 61 Left 2
WINDOW 0 -39 4 Left 2
SYMATTR Value 100µ
SYMATTR InstName C2
SYMATTR Description Capacitor
SYMATTR Type cap
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0.9 Lser=0
SYMBOL LED 1536 256 R270
WINDOW 0 72 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName LED1
SYMATTR Value LXZ1-PB01
SYMBOL res 976 432 M90
WINDOW 0 -2 59 VBottom 2
WINDOW 3 35 64 VTop 2
SYMATTR InstName R6
SYMATTR Value 220K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL cap 976 -144 M90
WINDOW 0 -3 31 VBottom 2
WINDOW 3 36 35 VTop 2
SYMATTR InstName C5
SYMATTR Value 0.01µ
SYMATTR SpiceLine V=16 Irms=291m Rser=0.34258 Lser=0
SYMBOL res 1248 368 M180
WINDOW 0 -40 81 Left 2
WINDOW 3 -51 46 Left 2
SYMATTR InstName R7
SYMATTR Value 470
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL schottky 1280 0 M0
WINDOW 0 43 24 Left 2
WINDOW 3 40 -8 Left 2
SYMATTR InstName D3
SYMATTR Value BAT54AHY
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL FerriteBead 1360 192 R0
SYMATTR InstName L2
SYMATTR Value 6µ
SYMATTR SpiceLine Ipk=3 Rser=0.0102 Rpar=1220 Cpar=1.9p
SYMBOL cap 1344 272 R0
SYMATTR InstName C4
SYMATTR Value 0.001µ
SYMATTR SpiceLine V=10 Irms=0 Rser=0.1909 Lser=177p mfg="Würth Elektronik"
pn="885012205006 WCAP-CSGP 0402" type="X7R"
SYMBOL LED 1696 256 R270
WINDOW 0 72 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName LED2
SYMATTR Value LXZ1-PB01
SYMBOL pnp 2256 -128 R180
SYMATTR InstName Q2
SYMATTR Value 2N3906
SYMBOL pnp 2416 -128 M180
SYMATTR InstName Q3
SYMATTR Value 2N3906
SYMBOL npn 2128 -16 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL npn 2544 -16 M0
SYMATTR InstName Q4
SYMATTR Value 2N3904
SYMBOL npn 2288 192 R0
SYMATTR InstName Q5
SYMATTR Value 2N3904
SYMBOL npn 2096 192 M0
SYMATTR InstName Q6
SYMATTR Value 2N3904
SYMBOL res 2016 -144 R0
SYMATTR InstName R10
SYMATTR Value 100K
TEXT 16 392 Left 2 !.tran 0.001 startup
piglet
2024-05-10 16:28:48 UTC
Permalink
Post by Edward Rawde
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
Startup behaviour is not ideal but maybe that can be fixed if it needs
fixing.
What's the cheapest op amp I can use for U2 instead of OP07?
Is there a cheaper comparator instead of LT1719 which will work?
Also the fet is bigger than it needs to ne.
Is there a better device for D4? Particularly if R4 can be reduced.
Will it work at all? Except in simulation.
I think I've answered my own question for the current controller but I don't
think it's feasible to attempt a discrete comparator on cost grounds.
Version 4
SHEET 1 3044 680
WIRE 2032 -272 64 -272
WIRE 2192 -272 2032 -272
WIRE 2480 -272 2192 -272
WIRE 2192 -224 2192 -272
WIRE 2480 -224 2480 -272
WIRE 2336 -176 2256 -176
WIRE 2416 -176 2336 -176
WIRE 976 -128 160 -128
WIRE 1072 -128 1040 -128
WIRE 2032 -128 2032 -272
WIRE 2192 -80 2192 -128
WIRE 2336 -80 2336 -176
WIRE 2336 -80 2192 -80
WIRE 2480 -64 2480 -128
WIRE 2688 -64 2480 -64
WIRE 16 -48 -16 -48
WIRE 64 -48 64 -272
WIRE 64 -48 16 -48
WIRE 96 -48 64 -48
WIRE 240 -48 96 -48
WIRE 336 -48 240 -48
WIRE 448 -48 336 -48
WIRE 464 -48 448 -48
WIRE 528 -48 464 -48
WIRE 608 -48 528 -48
WIRE 672 -48 608 -48
WIRE 784 -48 768 -48
WIRE 816 -48 784 -48
WIRE 864 -48 816 -48
WIRE 992 -48 944 -48
WIRE 1024 -48 992 -48
WIRE 1072 -48 1072 -128
WIRE 1072 -48 1024 -48
WIRE 1264 -48 1072 -48
WIRE 1360 -48 1264 -48
WIRE 240 -16 240 -48
WIRE 336 -16 336 -48
WIRE 2192 -16 2192 -80
WIRE 2480 -16 2480 -64
WIRE 1264 0 1264 -48
WIRE 1360 0 1360 -48
WIRE -16 32 -16 -48
WIRE 2128 32 1872 32
WIRE 2592 32 2544 32
WIRE 448 64 448 -48
WIRE 464 64 464 -48
WIRE 96 80 96 -48
WIRE 160 80 160 -128
WIRE 240 80 240 64
WIRE 240 80 160 80
WIRE 336 80 336 64
WIRE 384 80 336 80
WIRE 416 80 384 80
WIRE 816 80 816 -48
WIRE 992 80 992 -48
WIRE 336 96 336 80
WIRE 336 96 288 96
WIRE 656 96 480 96
WIRE 688 96 688 0
WIRE 688 96 656 96
WIRE 1264 96 1264 64
WIRE 1312 96 1264 96
WIRE 1936 96 1312 96
WIRE 240 112 240 80
WIRE 384 112 240 112
WIRE 416 112 384 112
WIRE 528 112 528 -48
WIRE 608 112 608 -48
WIRE 240 128 240 112
WIRE 336 128 336 96
WIRE 1360 128 1360 80
WIRE 1424 128 1360 128
WIRE 1872 128 1872 32
WIRE 1872 128 1424 128
WIRE 2192 128 2192 80
WIRE 2352 128 2192 128
WIRE 2480 128 2480 80
WIRE 2480 128 2352 128
WIRE 2032 144 2032 -48
WIRE 2128 144 2032 144
WIRE 1360 160 1360 128
WIRE -16 176 -16 112
WIRE 2032 192 2032 144
WIRE 2352 192 2352 128
WIRE 240 240 240 208
WIRE 336 240 336 208
WIRE 336 240 240 240
WIRE 384 240 336 240
WIRE 432 240 432 128
WIRE 432 240 384 240
WIRE 448 240 448 128
WIRE 448 240 432 240
WIRE 464 240 464 128
WIRE 464 240 448 240
WIRE 528 240 528 176
WIRE 528 240 464 240
WIRE 544 240 528 240
WIRE 608 240 608 176
WIRE 608 240 544 240
WIRE 1360 240 1360 224
WIRE 1424 240 1360 240
WIRE 1536 240 1424 240
WIRE 1696 240 1600 240
WIRE 1872 240 1760 240
WIRE 2128 240 2128 144
WIRE 2128 240 2096 240
WIRE 2288 240 2128 240
WIRE 544 272 544 240
WIRE 1264 272 1264 96
WIRE 1360 272 1360 240
WIRE -16 368 -16 256
WIRE 96 368 96 144
WIRE 96 368 -16 368
WIRE 544 368 544 352
WIRE 544 368 96 368
WIRE 816 368 816 144
WIRE 816 368 544 368
WIRE 992 368 992 144
WIRE 992 368 816 368
WIRE 1264 368 1264 352
WIRE 1264 368 992 368
WIRE 1360 368 1360 336
WIRE 1360 368 1264 368
WIRE 1872 368 1872 240
WIRE 1872 368 1360 368
WIRE 2032 368 2032 288
WIRE 2032 368 1872 368
WIRE 2352 368 2352 288
WIRE 2352 368 2032 368
WIRE -16 384 -16 368
WIRE 1936 400 1936 96
WIRE 2592 400 2592 32
WIRE 2592 400 1936 400
WIRE 288 448 288 96
WIRE 992 448 288 448
WIRE 1328 448 1072 448
WIRE 2688 448 2688 -64
WIRE 2688 448 1328 448
FLAG -16 384 0
FLAG 16 -48 in
FLAG 784 -48 sw
FLAG 1024 -48 out
FLAG 1424 128 isense
FLAG 1312 96 iref
FLAG 1328 448 ifb
FLAG 384 80 cmp-
FLAG 384 112 cmp+
FLAG 656 96 gate
FLAG 384 240 cmpv-
FLAG 1424 240 led
SYMBOL Comparators\\LT1719 448 32 R0
WINDOW 0 27 27 Left 2
WINDOW 3 -92 6 Left 2
SYMATTR InstName U1
SYMBOL res 320 112 R0
WINDOW 0 41 34 Left 2
WINDOW 3 35 64 Left 2
SYMATTR InstName R4
SYMATTR Value 10K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL ind 960 -64 R90
WINDOW 0 63 51 VBottom 2
WINDOW 3 -27 53 VTop 2
SYMATTR InstName L1
SYMATTR Value 68µ
SYMATTR SpiceLine Ipk=0.85 Rser=0.21 Rpar=0 Cpar=0 mfg="Sumida"
pn="CDR105B-680"
SYMBOL res 1376 -16 M0
WINDOW 0 -37 34 Left 2
WINDOW 3 -57 63 Left 2
SYMATTR InstName R8
SYMATTR Value 0.68
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL res 224 -32 R0
WINDOW 0 -35 19 Left 2
WINDOW 3 -49 48 Left 2
SYMATTR InstName R1
SYMATTR Value 10K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL schottky 832 144 R180
WINDOW 0 -42 30 Left 2
WINDOW 3 -119 -3 Left 2
SYMATTR InstName D2
SYMATTR Value MBRS130L
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL pmos 768 0 M270
WINDOW 0 10 129 VLeft 2
WINDOW 3 -10 67 VLeft 2
SYMATTR InstName M1
SYMATTR Value AO6407
SYMBOL voltage -16 160 R0
WINDOW 0 -75 16 Left 2
WINDOW 3 -71 54 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 -185 81 Left 2
SYMATTR InstName V3
SYMATTR Value 12
SYMBOL res -32 16 R0
WINDOW 0 -39 29 Left 2
WINDOW 3 -63 65 Left 2
SYMATTR InstName R9
SYMATTR Value 0.001
SYMBOL zener 544 176 R180
WINDOW 0 37 29 Left 2
WINDOW 3 68 -5 Right 2
SYMATTR InstName D1
SYMATTR Value UMZ5_1N
SYMBOL res 320 -32 R0
WINDOW 0 40 7 Left 2
WINDOW 3 37 33 Left 2
SYMATTR InstName R3
SYMATTR Value 10K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL res 528 368 M180
WINDOW 0 39 76 Left 2
WINDOW 3 38 42 Left 2
SYMATTR InstName R5
SYMATTR Value 220
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL cap 592 176 M180
WINDOW 0 29 52 Left 2
WINDOW 3 30 13 Left 2
SYMATTR InstName C3
SYMATTR Value 0.1µ
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0.0337 Lser=180p
SYMBOL polcap 976 80 R0
WINDOW 3 24 56 Left 2
WINDOW 0 27 9 Left 2
SYMATTR Value 100µ
SYMATTR InstName C1
SYMATTR Description Capacitor
SYMATTR Type cap
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0.9 Lser=0
SYMBOL res 224 112 R0
WINDOW 0 -40 33 Left 2
WINDOW 3 -52 57 Left 2
SYMATTR InstName R2
SYMATTR Value 10K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL polcap 80 80 R0
WINDOW 3 -57 61 Left 2
WINDOW 0 -39 4 Left 2
SYMATTR Value 100µ
SYMATTR InstName C2
SYMATTR Description Capacitor
SYMATTR Type cap
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0.9 Lser=0
SYMBOL LED 1536 256 R270
WINDOW 0 72 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName LED1
SYMATTR Value LXZ1-PB01
SYMBOL res 976 432 M90
WINDOW 0 -2 59 VBottom 2
WINDOW 3 35 64 VTop 2
SYMATTR InstName R6
SYMATTR Value 220K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL cap 976 -144 M90
WINDOW 0 -3 31 VBottom 2
WINDOW 3 36 35 VTop 2
SYMATTR InstName C5
SYMATTR Value 0.01µ
SYMATTR SpiceLine V=16 Irms=291m Rser=0.34258 Lser=0
SYMBOL res 1248 368 M180
WINDOW 0 -40 81 Left 2
WINDOW 3 -51 46 Left 2
SYMATTR InstName R7
SYMATTR Value 470
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL schottky 1280 0 M0
WINDOW 0 43 24 Left 2
WINDOW 3 40 -8 Left 2
SYMATTR InstName D3
SYMATTR Value BAT54AHY
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL FerriteBead 1360 192 R0
SYMATTR InstName L2
SYMATTR Value 6µ
SYMATTR SpiceLine Ipk=3 Rser=0.0102 Rpar=1220 Cpar=1.9p
SYMBOL cap 1344 272 R0
SYMATTR InstName C4
SYMATTR Value 0.001µ
SYMATTR SpiceLine V=10 Irms=0 Rser=0.1909 Lser=177p mfg="Würth Elektronik"
pn="885012205006 WCAP-CSGP 0402" type="X7R"
SYMBOL LED 1696 256 R270
WINDOW 0 72 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName LED2
SYMATTR Value LXZ1-PB01
SYMBOL pnp 2256 -128 R180
SYMATTR InstName Q2
SYMATTR Value 2N3906
SYMBOL pnp 2416 -128 M180
SYMATTR InstName Q3
SYMATTR Value 2N3906
SYMBOL npn 2128 -16 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL npn 2544 -16 M0
SYMATTR InstName Q4
SYMATTR Value 2N3904
SYMBOL npn 2288 192 R0
SYMATTR InstName Q5
SYMATTR Value 2N3904
SYMBOL npn 2096 192 M0
SYMATTR InstName Q6
SYMATTR Value 2N3904
SYMBOL res 2016 -144 R0
SYMATTR InstName R10
SYMATTR Value 100K
TEXT 16 392 Left 2 !.tran 0.001 startup
The venerable LM311 is still a good value comparator, if you want to
penny pinch omit the gate driver buffers and lower the pullup resistor
but efficiency will drop a lot from 85% to ca 72%.

Version 4
SHEET 1 996 708
WIRE -544 -112 -704 -112
WIRE -48 -112 -544 -112
WIRE 48 -112 -48 -112
WIRE 192 -112 48 -112
WIRE 336 -112 192 -112
WIRE 48 -96 48 -112
WIRE 192 -48 192 -112
WIRE -544 -16 -544 -112
WIRE 48 0 48 -16
WIRE 128 0 48 0
WIRE 336 64 336 -112
WIRE 192 80 192 48
WIRE 288 80 192 80
WIRE -544 176 -544 64
WIRE -448 176 -544 176
WIRE -240 224 -288 224
WIRE 336 224 336 160
WIRE 336 224 -160 224
WIRE -448 240 -448 176
WIRE 336 272 336 224
WIRE 416 272 336 272
WIRE 592 272 496 272
WIRE -704 320 -704 -112
WIRE 592 320 592 272
WIRE 592 320 416 320
WIRE -160 336 -192 336
WIRE -48 336 -48 -112
WIRE -48 336 -80 336
WIRE -544 352 -544 176
WIRE 592 352 592 320
WIRE 416 368 416 320
WIRE -48 384 -48 336
WIRE 192 384 192 80
WIRE -448 416 -448 320
WIRE -288 416 -288 224
WIRE -288 416 -448 416
WIRE -80 416 -288 416
WIRE 48 432 48 0
WIRE 48 432 0 432
WIRE 128 432 48 432
WIRE -192 448 -192 336
WIRE -80 448 -192 448
WIRE -448 464 -448 416
WIRE 336 464 336 272
WIRE 416 464 416 432
WIRE 592 464 592 416
WIRE 592 464 416 464
WIRE -192 496 -192 448
WIRE 592 496 592 464
WIRE -704 592 -704 400
WIRE -544 592 -544 416
WIRE -544 592 -704 592
WIRE -448 592 -448 544
WIRE -448 592 -544 592
WIRE -64 592 -64 480
WIRE -64 592 -448 592
WIRE -48 592 -48 480
WIRE -48 592 -64 592
WIRE 192 592 192 480
WIRE 192 592 -48 592
WIRE 336 592 336 528
WIRE 336 592 192 592
WIRE 592 592 592 576
WIRE 592 592 336 592
WIRE -704 640 -704 592
WIRE -192 672 -192 576
WIRE 416 672 416 464
WIRE 416 672 -192 672
FLAG -704 640 0
SYMBOL schottky 352 528 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D1
SYMATTR Value 1N5817
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL ind 400 288 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 5 56 VBottom 2
SYMATTR InstName L1
SYMATTR Value 0.22m
SYMATTR SpiceLine Rser=50m
SYMBOL LED 576 352 R0
SYMATTR InstName D2
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL voltage -704 304 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 12
SYMBOL res 576 480 R0
SYMATTR InstName R8
SYMATTR Value 0.15
SYMBOL zener -528 416 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D3
SYMATTR Value 1N750
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res -560 -32 R0
SYMATTR InstName R1
SYMATTR Value 2k
SYMBOL res -464 448 R0
SYMATTR InstName R3
SYMATTR Value 100
SYMBOL res -464 224 R0
SYMATTR InstName R2
SYMATTR Value 4.3k
SYMBOL res 32 -112 R0
SYMATTR InstName R7
SYMATTR Value 10k
SYMBOL cap 400 368 R0
SYMATTR InstName C1
SYMATTR Value 0.1m
SYMBOL res -144 208 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R4
SYMATTR Value 33k
SYMBOL res -176 592 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R5
SYMATTR Value 100
SYMBOL npn 128 -48 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL pnp 128 480 M180
SYMATTR InstName Q2
SYMATTR Value 2N3906
SYMBOL pmos 288 160 M180
SYMATTR InstName M2
SYMATTR Value AO6407
SYMBOL res -64 320 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R6
SYMATTR Value 33k
SYMBOL Comparators\\LT1011 -48 432 R0
SYMATTR InstName U2
TEXT -400 664 Left 2 !.tran 1m
TEXT 496 -96 Left 2 ;EPW SED MAY 2024
TEXT 496 -48 Left 2 ;LED BUCK USING LM311
TEXT -152 616 Left 2 ;R6 IS OPT LINE REGULATION FEED FWD CORR
TEXT -312 160 Left 2 ;R4 SETS HYSTERESIS
TEXT 472 616 Left 2 ;C1 OPT EMI/RFI FILT FOR REMOTE LED
TEXT -440 392 Left 2 ;VREF 100mV

piglet
Phil Hobbs
2024-05-10 17:17:23 UTC
Permalink
Post by piglet
Post by Edward Rawde
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
Startup behaviour is not ideal but maybe that can be fixed if it needs
fixing.
What's the cheapest op amp I can use for U2 instead of OP07?
Is there a cheaper comparator instead of LT1719 which will work?
Also the fet is bigger than it needs to ne.
Is there a better device for D4? Particularly if R4 can be reduced.
Will it work at all? Except in simulation.
I think I've answered my own question for the current controller but I don't
think it's feasible to attempt a discrete comparator on cost grounds.
Version 4
(Sniiip)
Post by piglet
The venerable LM311 is still a good value comparator, if you want to
penny pinch omit the gate driver buffers and lower the pullup resistor
but efficiency will drop a lot from 85% to ca 72%.
I’m not following through all the spicery, but fwiw:
The positive drive of an LM311 can be improved by 100x or more, by adding a
2-cent NPN and a 2-cent diode. The NPN is an emitter follower, and the
diode goes from base to emitter, reverse biases when the NPN is on.

It pulls down to a diode drop above ground, but that can be a Schottky, and
only has to handle the base bias, so it can be below 0.2 V, but you don’t
care about 0.7 V in a gate driver anyway.

When the 311 goes low, the diode doesn’t start conducting till the
transistor is off, and there’s no stored charge to worry about, since the
NPN never saturates.

Cheers

Phil Hobbs
--
Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC /
Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics
Phil Hobbs
2024-05-10 17:20:01 UTC
Permalink
Post by Phil Hobbs
Post by piglet
Post by Edward Rawde
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
Startup behaviour is not ideal but maybe that can be fixed if it needs
fixing.
What's the cheapest op amp I can use for U2 instead of OP07?
Is there a cheaper comparator instead of LT1719 which will work?
Also the fet is bigger than it needs to ne.
Is there a better device for D4? Particularly if R4 can be reduced.
Will it work at all? Except in simulation.
I think I've answered my own question for the current controller but I don't
think it's feasible to attempt a discrete comparator on cost grounds.
Version 4
(Sniiip)
Post by piglet
The venerable LM311 is still a good value comparator, if you want to
penny pinch omit the gate driver buffers and lower the pullup resistor
but efficiency will drop a lot from 85% to ca 72%.
The positive drive of an LM311 can be improved by 100x or more, by adding a
2-cent NPN and a 2-cent diode. The NPN is an emitter follower, and the
diode goes from base to emitter, reverse biases when the NPN is on.
It pulls down to a diode drop above ground, but that can be a Schottky, and
only has to handle the base bias, so it can be below 0.2 V, but you don’t
care about 0.7 V in a gate driver anyway.
When the 311 goes low, the diode doesn’t start conducting till the
transistor is off, and there’s no stored charge to worry about, since the
NPN never saturates.
Oh, and take the output from the emitter.

Cheers

Phil Hobbs
--
Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC /
Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics
piglet
2024-05-10 20:16:56 UTC
Permalink
Post by Phil Hobbs
Post by Phil Hobbs
Post by piglet
Post by Edward Rawde
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
Startup behaviour is not ideal but maybe that can be fixed if it needs
fixing.
What's the cheapest op amp I can use for U2 instead of OP07?
Is there a cheaper comparator instead of LT1719 which will work?
Also the fet is bigger than it needs to ne.
Is there a better device for D4? Particularly if R4 can be reduced.
Will it work at all? Except in simulation.
I think I've answered my own question for the current controller but I don't
think it's feasible to attempt a discrete comparator on cost grounds.
Version 4
(Sniiip)
Post by piglet
The venerable LM311 is still a good value comparator, if you want to
penny pinch omit the gate driver buffers and lower the pullup resistor
but efficiency will drop a lot from 85% to ca 72%.
The positive drive of an LM311 can be improved by 100x or more, by adding a
2-cent NPN and a 2-cent diode. The NPN is an emitter follower, and the
diode goes from base to emitter, reverse biases when the NPN is on.
It pulls down to a diode drop above ground, but that can be a Schottky, and
only has to handle the base bias, so it can be below 0.2 V, but you don’t
care about 0.7 V in a gate driver anyway.
When the 311 goes low, the diode doesn’t start conducting till the
transistor is off, and there’s no stored charge to worry about, since the
NPN never saturates.
Oh, and take the output from the emitter.
Cheers
Phil Hobbs
Right , I actually did as you described in an earlier version but a PNP is
practically the same cost as a diode and provides added beef.
--
piglet
Edward Rawde
2024-05-10 18:57:03 UTC
Permalink
Post by Edward Rawde
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
Startup behaviour is not ideal but maybe that can be fixed if it needs
fixing.
What's the cheapest op amp I can use for U2 instead of OP07?
Is there a cheaper comparator instead of LT1719 which will work?
Also the fet is bigger than it needs to ne.
Is there a better device for D4? Particularly if R4 can be reduced.
Will it work at all? Except in simulation.
I think I've answered my own question for the current controller but I don't
think it's feasible to attempt a discrete comparator on cost grounds.
...
The venerable LM311 is still a good value comparator, if you want to penny
pinch omit the gate driver buffers and lower the pullup resistor but
efficiency will drop a lot from 85% to ca 72%.
Thanks, that works but I was hoping for a smaller inductor at about 1MHz and
filtered LED feed referenced to ground for up to three LEDs.

I'm probably done with my circuit unless there's a cheaper comparator which
can do the same job or a cheaper op amp which can run on lead acid voltage.
Or preferably up to 15V.
Also a cheaper fet.
piglet
2024-05-10 20:26:11 UTC
Permalink
Post by Edward Rawde
Post by Edward Rawde
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
Startup behaviour is not ideal but maybe that can be fixed if it needs
fixing.
What's the cheapest op amp I can use for U2 instead of OP07?
Is there a cheaper comparator instead of LT1719 which will work?
Also the fet is bigger than it needs to ne.
Is there a better device for D4? Particularly if R4 can be reduced.
Will it work at all? Except in simulation.
I think I've answered my own question for the current controller but I don't
think it's feasible to attempt a discrete comparator on cost grounds.
...
The venerable LM311 is still a good value comparator, if you want to penny
pinch omit the gate driver buffers and lower the pullup resistor but
efficiency will drop a lot from 85% to ca 72%.
Thanks, that works but I was hoping for a smaller inductor at about 1MHz and
filtered LED feed referenced to ground for up to three LEDs.
I'm probably done with my circuit unless there's a cheaper comparator which
can do the same job or a cheaper op amp which can run on lead acid voltage.
Or preferably up to 15V.
Also a cheaper fet.
Ground referenced output is possible, rearrange the sense resistor and
stand the reference on top of the LEDs. As in ...

Version 4
SHEET 1 996 708
WIRE -544 -112 -704 -112
WIRE -48 -112 -544 -112
WIRE 48 -112 -48 -112
WIRE 192 -112 48 -112
WIRE 336 -112 192 -112
WIRE 48 -96 48 -112
WIRE 192 -48 192 -112
WIRE -544 -16 -544 -112
WIRE 48 0 48 -16
WIRE 128 0 48 0
WIRE 336 64 336 -112
WIRE 192 80 192 48
WIRE 288 80 192 80
WIRE -544 176 -544 64
WIRE -448 176 -544 176
WIRE -240 224 -288 224
WIRE 336 224 336 160
WIRE 336 224 -160 224
WIRE -448 240 -448 176
WIRE 336 272 336 224
WIRE 416 272 336 272
WIRE 528 272 496 272
WIRE 624 272 528 272
WIRE -704 320 -704 -112
WIRE 528 320 528 272
WIRE 528 320 400 320
WIRE 624 320 624 272
WIRE -160 336 -192 336
WIRE -48 336 -48 -112
WIRE -48 336 -80 336
WIRE -544 352 -544 176
WIRE -48 384 -48 336
WIRE 192 384 192 80
WIRE -448 416 -448 320
WIRE -288 416 -288 224
WIRE -288 416 -448 416
WIRE -80 416 -288 416
WIRE 48 432 48 0
WIRE 48 432 0 432
WIRE 128 432 48 432
WIRE -192 448 -192 336
WIRE -80 448 -192 448
WIRE 480 448 432 448
WIRE 624 448 624 400
WIRE 624 448 480 448
WIRE -448 464 -448 416
WIRE 336 464 336 272
WIRE 624 480 624 448
WIRE -192 496 -192 448
WIRE 480 496 480 448
WIRE -544 560 -544 416
WIRE -448 560 -448 544
WIRE -448 560 -544 560
WIRE -704 592 -704 400
WIRE -64 592 -64 480
WIRE -64 592 -704 592
WIRE -48 592 -48 480
WIRE -48 592 -64 592
WIRE 192 592 192 480
WIRE 192 592 -48 592
WIRE 336 592 336 528
WIRE 336 592 192 592
WIRE 480 592 480 560
WIRE 480 592 336 592
WIRE 624 592 624 544
WIRE 624 592 480 592
WIRE -704 640 -704 592
WIRE -192 672 -192 576
WIRE 400 672 400 320
WIRE 400 672 -192 672
WIRE -448 688 -448 560
WIRE 432 688 432 448
WIRE 432 688 -448 688
FLAG -704 640 0
SYMBOL schottky 352 528 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D1
SYMATTR Value 1N5817
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL ind 400 288 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 5 56 VBottom 2
SYMATTR InstName L1
SYMATTR Value 0.22m
SYMATTR SpiceLine Rser=50m
SYMBOL LED 608 480 R0
SYMATTR InstName D2
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL voltage -704 304 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 12
SYMBOL res 608 304 R0
SYMATTR InstName R8
SYMATTR Value 0.15
SYMBOL zener -528 416 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D3
SYMATTR Value 1N750
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res -560 -32 R0
SYMATTR InstName R1
SYMATTR Value 2k
SYMBOL res -464 448 R0
SYMATTR InstName R3
SYMATTR Value 100
SYMBOL res -464 224 R0
SYMATTR InstName R2
SYMATTR Value 4.3k
SYMBOL res 32 -112 R0
SYMATTR InstName R7
SYMATTR Value 10k
SYMBOL cap 464 496 R0
SYMATTR InstName C1
SYMATTR Value 0.1m
SYMBOL res -144 208 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R4
SYMATTR Value 33k
SYMBOL res -176 592 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R5
SYMATTR Value 100
SYMBOL npn 128 -48 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL pnp 128 480 M180
SYMATTR InstName Q2
SYMATTR Value 2N3906
SYMBOL pmos 288 160 M180
SYMATTR InstName M2
SYMATTR Value AO6407
SYMBOL res -64 320 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R6
SYMATTR Value 33k
SYMBOL Comparators\\LT1011 -48 432 R0
SYMATTR InstName U2
TEXT 664 672 Left 2 !.tran 1m
TEXT 496 -96 Left 2 ;EPW SED MAY 2024
TEXT 496 -48 Left 2 ;LED BUCK USING LM311
TEXT -152 616 Left 2 ;R6 IS OPT LINE REGULATION FEED FWD CORR
TEXT -312 160 Left 2 ;R4 SETS HYSTERESIS
TEXT 472 616 Left 2 ;C1 OPT EMI/RFI FILT FOR REMOTE LED
TEXT -440 392 Left 2 ;VREF 100mV

piglet
John Larkin
2024-05-10 18:35:35 UTC
Permalink
On Thu, 9 May 2024 23:11:03 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
Startup behaviour is not ideal but maybe that can be fixed if it needs
fixing.
What's the cheapest op amp I can use for U2 instead of OP07?
Is there a cheaper comparator instead of LT1719 which will work?
Also the fet is bigger than it needs to ne.
Is there a better device for D4? Particularly if R4 can be reduced.
Will it work at all? Except in simulation.
I think I've answered my own question for the current controller but I don't
think it's feasible to attempt a discrete comparator on cost grounds.
I think the LED constant-current switcher can be done with a pfet and
two NPN transistors.
Edward Rawde
2024-05-10 21:03:23 UTC
Permalink
Post by John Larkin
On Thu, 9 May 2024 23:11:03 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
Startup behaviour is not ideal but maybe that can be fixed if it needs
fixing.
What's the cheapest op amp I can use for U2 instead of OP07?
Is there a cheaper comparator instead of LT1719 which will work?
Also the fet is bigger than it needs to ne.
Is there a better device for D4? Particularly if R4 can be reduced.
Will it work at all? Except in simulation.
I think I've answered my own question for the current controller but I don't
think it's feasible to attempt a discrete comparator on cost grounds.
I think the LED constant-current switcher can be done with a pfet and
two NPN transistors.
Ok here's the spec.

Input voltage range 10.5V to 12.6 V. Preferably 10V to 15V.

Minimum efficiency. 80%

Inductor not bigger than 68uH 1A. Preferably smaller.

One, two or three LEDs at 500mA +/- 50mA

Filtered LED feed referenced to ground.

Maximum total LED wiring length. 12 inches.

EMC compliant in all countries.

Cost. Minimum which will meet spec.
piglet
2024-05-10 21:40:29 UTC
Permalink
Post by Edward Rawde
Post by John Larkin
On Thu, 9 May 2024 23:11:03 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
Startup behaviour is not ideal but maybe that can be fixed if it needs
fixing.
What's the cheapest op amp I can use for U2 instead of OP07?
Is there a cheaper comparator instead of LT1719 which will work?
Also the fet is bigger than it needs to ne.
Is there a better device for D4? Particularly if R4 can be reduced.
Will it work at all? Except in simulation.
I think I've answered my own question for the current controller but I don't
think it's feasible to attempt a discrete comparator on cost grounds.
I think the LED constant-current switcher can be done with a pfet and
two NPN transistors.
Ok here's the spec.
Input voltage range 10.5V to 12.6 V. Preferably 10V to 15V.
Minimum efficiency. 80%
Inductor not bigger than 68uH 1A. Preferably smaller.
One, two or three LEDs at 500mA +/- 50mA
Filtered LED feed referenced to ground.
Maximum total LED wiring length. 12 inches.
EMC compliant in all countries.
Cost. Minimum which will meet spec.
My LM311 based idea works ok with 68uH inductors too. Efficiency is above
80% for supply 10 to 13V and still 77% at 16V

Haven’t explored 1, 2 or 3 LED outputs.

You didn’t say if “ground” was input negative or positive but if positive
ground then flip the circuit over and use a cheaper N-channel FET :)

The input to a buck converter is pulsed current - you have mentioned output
leads but some, possibly extensive, filtering will be needed on the input.

Pay me for EMC compliance :)
--
piglet
Edward Rawde
2024-05-10 22:05:10 UTC
Permalink
Post by piglet
Post by Edward Rawde
Post by John Larkin
On Thu, 9 May 2024 23:11:03 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
Startup behaviour is not ideal but maybe that can be fixed if it needs
fixing.
What's the cheapest op amp I can use for U2 instead of OP07?
Is there a cheaper comparator instead of LT1719 which will work?
Also the fet is bigger than it needs to ne.
Is there a better device for D4? Particularly if R4 can be reduced.
Will it work at all? Except in simulation.
I think I've answered my own question for the current controller but I don't
think it's feasible to attempt a discrete comparator on cost grounds.
I think the LED constant-current switcher can be done with a pfet and
two NPN transistors.
Ok here's the spec.
Input voltage range 10.5V to 12.6 V. Preferably 10V to 15V.
Minimum efficiency. 80%
Inductor not bigger than 68uH 1A. Preferably smaller.
One, two or three LEDs at 500mA +/- 50mA
Filtered LED feed referenced to ground.
Maximum total LED wiring length. 12 inches.
EMC compliant in all countries.
Cost. Minimum which will meet spec.
My LM311 based idea works ok with 68uH inductors too. Efficiency is above
80% for supply 10 to 13V and still 77% at 16V
Haven't explored 1, 2 or 3 LED outputs.
You didn't say if "ground" was input negative or positive but if positive
ground then flip the circuit over and use a cheaper N-channel FET :)
Ground is input negative.
Post by piglet
The input to a buck converter is pulsed current - you have mentioned output
leads but some, possibly extensive, filtering will be needed on the input.
Yes it crossed my mind that the input may need EMC filtering too.
Post by piglet
Pay me for EMC compliance :)
As long as it doesn't go in circles with filter this, failed again, filter
that, failed again, change the layout, failed again, etc
Post by piglet
--
piglet
Edward Rawde
2024-05-10 22:17:47 UTC
Permalink
Post by piglet
Post by Edward Rawde
Post by John Larkin
On Thu, 9 May 2024 23:11:03 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
Startup behaviour is not ideal but maybe that can be fixed if it needs
fixing.
What's the cheapest op amp I can use for U2 instead of OP07?
Is there a cheaper comparator instead of LT1719 which will work?
Also the fet is bigger than it needs to ne.
Is there a better device for D4? Particularly if R4 can be reduced.
Will it work at all? Except in simulation.
I think I've answered my own question for the current controller but I don't
think it's feasible to attempt a discrete comparator on cost grounds.
I think the LED constant-current switcher can be done with a pfet and
two NPN transistors.
Ok here's the spec.
Input voltage range 10.5V to 12.6 V. Preferably 10V to 15V.
Minimum efficiency. 80%
Inductor not bigger than 68uH 1A. Preferably smaller.
One, two or three LEDs at 500mA +/- 50mA
Filtered LED feed referenced to ground.
Maximum total LED wiring length. 12 inches.
EMC compliant in all countries.
Cost. Minimum which will meet spec.
My LM311 based idea works ok with 68uH inductors too. Efficiency is above
80% for supply 10 to 13V and still 77% at 16V
Haven't explored 1, 2 or 3 LED outputs.
You didn't say if "ground" was input negative or positive but if positive
ground then flip the circuit over and use a cheaper N-channel FET :)
The input to a buck converter is pulsed current - you have mentioned output
leads but some, possibly extensive, filtering will be needed on the input.
That makes me wonder whether the input could be made near enough DC by using
two converters.
One taking current when the other isn't. Perhaps two LEDs each.

Thanks for all your input. I think I'm just about done with this unless John
Larkin want to show his pfet and one npn circuit.
Post by piglet
Pay me for EMC compliance :)
--
piglet
Edward Rawde
2024-05-11 03:00:30 UTC
Permalink
Post by John Larkin
On Thu, 9 May 2024 23:11:03 -0400, "Edward Rawde"
....

Simulation says that these synchronize in opposite phase.
As expected there is overlap causing input current spikes and there's
probably no way to fix that.
I wonder what would happen in reality.

Version 4
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TEXT -160 392 Left 2 !.tran 0.001 startup
John Larkin
2024-05-11 14:29:26 UTC
Permalink
On Fri, 10 May 2024 18:17:47 -0400, "Edward Rawde"
Post by Edward Rawde
Post by piglet
Post by Edward Rawde
Post by John Larkin
On Thu, 9 May 2024 23:11:03 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
Startup behaviour is not ideal but maybe that can be fixed if it needs
fixing.
What's the cheapest op amp I can use for U2 instead of OP07?
Is there a cheaper comparator instead of LT1719 which will work?
Also the fet is bigger than it needs to ne.
Is there a better device for D4? Particularly if R4 can be reduced.
Will it work at all? Except in simulation.
I think I've answered my own question for the current controller but I don't
think it's feasible to attempt a discrete comparator on cost grounds.
I think the LED constant-current switcher can be done with a pfet and
two NPN transistors.
Ok here's the spec.
Input voltage range 10.5V to 12.6 V. Preferably 10V to 15V.
Minimum efficiency. 80%
Inductor not bigger than 68uH 1A. Preferably smaller.
One, two or three LEDs at 500mA +/- 50mA
Filtered LED feed referenced to ground.
Maximum total LED wiring length. 12 inches.
EMC compliant in all countries.
Cost. Minimum which will meet spec.
My LM311 based idea works ok with 68uH inductors too. Efficiency is above
80% for supply 10 to 13V and still 77% at 16V
Haven't explored 1, 2 or 3 LED outputs.
You didn't say if "ground" was input negative or positive but if positive
ground then flip the circuit over and use a cheaper N-channel FET :)
The input to a buck converter is pulsed current - you have mentioned output
leads but some, possibly extensive, filtering will be needed on the input.
That makes me wonder whether the input could be made near enough DC by using
two converters.
One taking current when the other isn't. Perhaps two LEDs each.
Thanks for all your input. I think I'm just about done with this unless John
Larkin want to show his pfet and one npn circuit.
Post by piglet
Pay me for EMC compliance :)
--
piglet
Something like this should work.

Loading Image...

But I'd rather use a TPS562208, which would be cheaper and simpler and
has spread-spectrum to help the EMC thing by about 20 dB.
piglet
2024-05-11 15:04:15 UTC
Permalink
Post by John Larkin
On Fri, 10 May 2024 18:17:47 -0400, "Edward Rawde"
Post by Edward Rawde
Post by piglet
Post by Edward Rawde
Post by John Larkin
On Thu, 9 May 2024 23:11:03 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
Startup behaviour is not ideal but maybe that can be fixed if it needs
fixing.
What's the cheapest op amp I can use for U2 instead of OP07?
Is there a cheaper comparator instead of LT1719 which will work?
Also the fet is bigger than it needs to ne.
Is there a better device for D4? Particularly if R4 can be reduced.
Will it work at all? Except in simulation.
I think I've answered my own question for the current controller but I don't
think it's feasible to attempt a discrete comparator on cost grounds.
I think the LED constant-current switcher can be done with a pfet and
two NPN transistors.
Ok here's the spec.
Input voltage range 10.5V to 12.6 V. Preferably 10V to 15V.
Minimum efficiency. 80%
Inductor not bigger than 68uH 1A. Preferably smaller.
One, two or three LEDs at 500mA +/- 50mA
Filtered LED feed referenced to ground.
Maximum total LED wiring length. 12 inches.
EMC compliant in all countries.
Cost. Minimum which will meet spec.
My LM311 based idea works ok with 68uH inductors too. Efficiency is above
80% for supply 10 to 13V and still 77% at 16V
Haven't explored 1, 2 or 3 LED outputs.
You didn't say if "ground" was input negative or positive but if positive
ground then flip the circuit over and use a cheaper N-channel FET :)
The input to a buck converter is pulsed current - you have mentioned output
leads but some, possibly extensive, filtering will be needed on the input.
That makes me wonder whether the input could be made near enough DC by using
two converters.
One taking current when the other isn't. Perhaps two LEDs each.
Thanks for all your input. I think I'm just about done with this unless John
Larkin want to show his pfet and one npn circuit.
Post by piglet
Pay me for EMC compliance :)
--
piglet
Something like this should work.
https://www.dropbox.com/scl/fi/su03d8gaxbi67zhufz3th/LED_CC_Reg_1.jpg?rlkey=oh4ib9011ee1c74ih7hk7dzcb&raw=1
But I'd rather use a TPS562208, which would be cheaper and simpler and
has spread-spectrum to help the EMC thing by about 20 dB.
Yes, my take is not too far distant but I tried to accomodate the OP's
unexplained desire for ground referenced LED output.

Version 4
SHEET 1 1044 708
WIRE -144 -112 -432 -112
WIRE 64 -112 -144 -112
WIRE 176 -112 64 -112
WIRE -144 -96 -144 -112
WIRE 64 -80 64 -112
WIRE -144 16 -144 -16
WIRE -144 16 -224 16
WIRE 176 16 176 -112
WIRE 64 32 64 0
WIRE 128 32 64 32
WIRE -144 48 -144 16
WIRE 176 144 176 112
WIRE 272 144 176 144
WIRE -224 176 -224 16
WIRE -144 176 -144 128
WIRE -64 176 -144 176
WIRE 176 176 176 144
WIRE 176 176 16 176
WIRE 176 208 176 176
WIRE 64 224 64 32
WIRE -144 272 -144 176
WIRE 0 272 -144 272
WIRE -432 320 -432 -112
WIRE -144 320 -144 272
WIRE 176 320 176 288
WIRE 176 320 64 320
WIRE 176 336 176 320
WIRE -144 432 -144 384
WIRE -48 432 -144 432
WIRE 176 432 176 416
WIRE 176 432 32 432
WIRE 352 432 176 432
WIRE 448 432 352 432
WIRE 352 480 352 432
WIRE 448 480 448 432
WIRE 272 496 272 144
WIRE -432 592 -432 400
WIRE -224 592 -224 240
WIRE -224 592 -432 592
WIRE 272 592 272 560
WIRE 272 592 -224 592
WIRE 352 592 352 544
WIRE 352 592 272 592
WIRE 448 592 448 544
WIRE 448 592 352 592
WIRE -432 640 -432 592
FLAG -432 640 0
FLAG 448 432 OUT
SYMBOL schottky 288 560 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D3
SYMATTR Value 1N5817
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL ind 160 192 R0
SYMATTR InstName L1
SYMATTR Value 0.068m
SYMATTR SpiceLine Rser=50m
SYMBOL LED 432 480 R0
SYMATTR InstName D4
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL voltage -432 304 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 12
SYMBOL res 160 320 R0
SYMATTR InstName R6
SYMATTR Value 0.15
SYMBOL cap 336 480 R0
SYMATTR InstName C1
SYMATTR Value 0.1m
SYMBOL npn 0 224 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL res -64 448 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R4
SYMATTR Value 330
SYMBOL res 32 160 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 47k
SYMBOL pmos 128 112 M180
SYMATTR InstName M1
SYMATTR Value AO6407
SYMBOL res 48 -96 R0
SYMATTR InstName R5
SYMATTR Value 330
SYMBOL res -160 32 R0
SYMATTR InstName R2
SYMATTR Value 3.9k
SYMBOL diode -160 320 R0
SYMATTR InstName D2
SYMATTR Value 1N914
SYMBOL res -160 -112 R0
SYMATTR InstName R1
SYMATTR Value 330
SYMBOL zener -208 240 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D1
SYMATTR Value BZX84B6V2L
SYMATTR Description Diode
SYMATTR Type diode
TEXT 544 664 Left 2 !.tran 1m
TEXT 368 -88 Left 2 ;EPW SED MAY 2024
TEXT 368 -32 Left 2 ;LED BUCK USING 1Q 1PFET
TEXT -312 624 Left 2 ;R1 D1 IMPROVE LINE REG
TEXT -312 664 Left 2 ;D2 APPROX TC COMP Q1
TEXT 368 24 Left 2 ;NON OPTIMISED BUT SHOWS IT CAN BE DONE

piglet
John Larkin
2024-05-11 16:42:48 UTC
Permalink
Post by piglet
Post by John Larkin
On Fri, 10 May 2024 18:17:47 -0400, "Edward Rawde"
Post by Edward Rawde
Post by piglet
Post by Edward Rawde
Post by John Larkin
On Thu, 9 May 2024 23:11:03 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
Startup behaviour is not ideal but maybe that can be fixed if it needs
fixing.
What's the cheapest op amp I can use for U2 instead of OP07?
Is there a cheaper comparator instead of LT1719 which will work?
Also the fet is bigger than it needs to ne.
Is there a better device for D4? Particularly if R4 can be reduced.
Will it work at all? Except in simulation.
I think I've answered my own question for the current controller but I don't
think it's feasible to attempt a discrete comparator on cost grounds.
I think the LED constant-current switcher can be done with a pfet and
two NPN transistors.
Ok here's the spec.
Input voltage range 10.5V to 12.6 V. Preferably 10V to 15V.
Minimum efficiency. 80%
Inductor not bigger than 68uH 1A. Preferably smaller.
One, two or three LEDs at 500mA +/- 50mA
Filtered LED feed referenced to ground.
Maximum total LED wiring length. 12 inches.
EMC compliant in all countries.
Cost. Minimum which will meet spec.
My LM311 based idea works ok with 68uH inductors too. Efficiency is above
80% for supply 10 to 13V and still 77% at 16V
Haven't explored 1, 2 or 3 LED outputs.
You didn't say if "ground" was input negative or positive but if positive
ground then flip the circuit over and use a cheaper N-channel FET :)
The input to a buck converter is pulsed current - you have mentioned output
leads but some, possibly extensive, filtering will be needed on the input.
That makes me wonder whether the input could be made near enough DC by using
two converters.
One taking current when the other isn't. Perhaps two LEDs each.
Thanks for all your input. I think I'm just about done with this unless John
Larkin want to show his pfet and one npn circuit.
Post by piglet
Pay me for EMC compliance :)
--
piglet
Something like this should work.
https://www.dropbox.com/scl/fi/su03d8gaxbi67zhufz3th/LED_CC_Reg_1.jpg?rlkey=oh4ib9011ee1c74ih7hk7dzcb&raw=1
But I'd rather use a TPS562208, which would be cheaper and simpler and
has spread-spectrum to help the EMC thing by about 20 dB.
Yes, my take is not too far distant but I tried to accomodate the OP's
unexplained desire for ground referenced LED output.
That's nice. It's only an LED, so it probably doesn't need +12v
compensation.

LEDs lose light as temperature rises, so it probably doesn't need Vbe
temp compensation either. I'm glad that you saw the hysteresis trick,
and that you drew a decent looking schematic with a title, date, and
author.

We have one project here that has had three or four project engineers
so far, and the project folder contains 175 (yes, 175!) .asc files,
most of which are hideous uncommented messes.

My sim will be # 176.

Loading Image...

It's a dual isolated programmable DC power supply, but it has remote
sense and a paralleling relay, which complicate life. We don't know
what bizarre loads the user will have, or if they will connect the
remote sense right.

Sims run super slow and there are many cases to test, so we set up
three monster PCs in the conference room as a simulator farm, to
supplement the two we will use in engineers offices.
piglet
2024-05-11 17:27:33 UTC
Permalink
Post by John Larkin
Post by piglet
Post by John Larkin
On Fri, 10 May 2024 18:17:47 -0400, "Edward Rawde"
Post by Edward Rawde
Post by piglet
Post by Edward Rawde
Post by John Larkin
On Thu, 9 May 2024 23:11:03 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
Startup behaviour is not ideal but maybe that can be fixed if it needs
fixing.
What's the cheapest op amp I can use for U2 instead of OP07?
Is there a cheaper comparator instead of LT1719 which will work?
Also the fet is bigger than it needs to ne.
Is there a better device for D4? Particularly if R4 can be reduced.
Will it work at all? Except in simulation.
I think I've answered my own question for the current controller but I don't
think it's feasible to attempt a discrete comparator on cost grounds.
I think the LED constant-current switcher can be done with a pfet and
two NPN transistors.
Ok here's the spec.
Input voltage range 10.5V to 12.6 V. Preferably 10V to 15V.
Minimum efficiency. 80%
Inductor not bigger than 68uH 1A. Preferably smaller.
One, two or three LEDs at 500mA +/- 50mA
Filtered LED feed referenced to ground.
Maximum total LED wiring length. 12 inches.
EMC compliant in all countries.
Cost. Minimum which will meet spec.
My LM311 based idea works ok with 68uH inductors too. Efficiency is above
80% for supply 10 to 13V and still 77% at 16V
Haven't explored 1, 2 or 3 LED outputs.
You didn't say if "ground" was input negative or positive but if positive
ground then flip the circuit over and use a cheaper N-channel FET :)
The input to a buck converter is pulsed current - you have mentioned output
leads but some, possibly extensive, filtering will be needed on the input.
That makes me wonder whether the input could be made near enough DC by using
two converters.
One taking current when the other isn't. Perhaps two LEDs each.
Thanks for all your input. I think I'm just about done with this unless John
Larkin want to show his pfet and one npn circuit.
Post by piglet
Pay me for EMC compliance :)
--
piglet
Something like this should work.
https://www.dropbox.com/scl/fi/su03d8gaxbi67zhufz3th/LED_CC_Reg_1.jpg?rlkey=oh4ib9011ee1c74ih7hk7dzcb&raw=1
But I'd rather use a TPS562208, which would be cheaper and simpler and
has spread-spectrum to help the EMC thing by about 20 dB.
Yes, my take is not too far distant but I tried to accomodate the OP's
unexplained desire for ground referenced LED output.
That's nice. It's only an LED, so it probably doesn't need +12v
compensation.
LEDs lose light as temperature rises, so it probably doesn't need Vbe
temp compensation either. I'm glad that you saw the hysteresis trick,
and that you drew a decent looking schematic with a title, date, and
author.
We have one project here that has had three or four project engineers
so far, and the project folder contains 175 (yes, 175!) .asc files,
most of which are hideous uncommented messes.
My sim will be # 176.
https://www.dropbox.com/scl/fi/i1rmnne2j2f2nhetfg1dn/P941C_May11.jpg?rlkey=9by4bmkzo6iim763468y21ko2&raw=1
It's a dual isolated programmable DC power supply, but it has remote
sense and a paralleling relay, which complicate life. We don't know
what bizarre loads the user will have, or if they will connect the
remote sense right.
Sims run super slow and there are many cases to test, so we set up
three monster PCs in the conference room as a simulator farm, to
supplement the two we will use in engineers offices.
Thanks.

Compensating feedback systems to cope with wide ranging capacitive loads
is awkward. I have good results with Phil Perkins stacked RC 3dB/octave
method.

piglet
John Larkin
2024-05-11 17:51:59 UTC
Permalink
Post by piglet
Post by John Larkin
Post by piglet
Post by John Larkin
On Fri, 10 May 2024 18:17:47 -0400, "Edward Rawde"
Post by Edward Rawde
Post by piglet
Post by Edward Rawde
Post by John Larkin
On Thu, 9 May 2024 23:11:03 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
Startup behaviour is not ideal but maybe that can be fixed if it needs
fixing.
What's the cheapest op amp I can use for U2 instead of OP07?
Is there a cheaper comparator instead of LT1719 which will work?
Also the fet is bigger than it needs to ne.
Is there a better device for D4? Particularly if R4 can be reduced.
Will it work at all? Except in simulation.
I think I've answered my own question for the current controller but I
don't
think it's feasible to attempt a discrete comparator on cost grounds.
I think the LED constant-current switcher can be done with a pfet and
two NPN transistors.
Ok here's the spec.
Input voltage range 10.5V to 12.6 V. Preferably 10V to 15V.
Minimum efficiency. 80%
Inductor not bigger than 68uH 1A. Preferably smaller.
One, two or three LEDs at 500mA +/- 50mA
Filtered LED feed referenced to ground.
Maximum total LED wiring length. 12 inches.
EMC compliant in all countries.
Cost. Minimum which will meet spec.
My LM311 based idea works ok with 68uH inductors too. Efficiency is above
80% for supply 10 to 13V and still 77% at 16V
Haven't explored 1, 2 or 3 LED outputs.
You didn't say if "ground" was input negative or positive but if positive
ground then flip the circuit over and use a cheaper N-channel FET :)
The input to a buck converter is pulsed current - you have mentioned output
leads but some, possibly extensive, filtering will be needed on the input.
That makes me wonder whether the input could be made near enough DC by using
two converters.
One taking current when the other isn't. Perhaps two LEDs each.
Thanks for all your input. I think I'm just about done with this unless John
Larkin want to show his pfet and one npn circuit.
Post by piglet
Pay me for EMC compliance :)
--
piglet
Something like this should work.
https://www.dropbox.com/scl/fi/su03d8gaxbi67zhufz3th/LED_CC_Reg_1.jpg?rlkey=oh4ib9011ee1c74ih7hk7dzcb&raw=1
But I'd rather use a TPS562208, which would be cheaper and simpler and
has spread-spectrum to help the EMC thing by about 20 dB.
Yes, my take is not too far distant but I tried to accomodate the OP's
unexplained desire for ground referenced LED output.
That's nice. It's only an LED, so it probably doesn't need +12v
compensation.
LEDs lose light as temperature rises, so it probably doesn't need Vbe
temp compensation either. I'm glad that you saw the hysteresis trick,
and that you drew a decent looking schematic with a title, date, and
author.
We have one project here that has had three or four project engineers
so far, and the project folder contains 175 (yes, 175!) .asc files,
most of which are hideous uncommented messes.
My sim will be # 176.
https://www.dropbox.com/scl/fi/i1rmnne2j2f2nhetfg1dn/P941C_May11.jpg?rlkey=9by4bmkzo6iim763468y21ko2&raw=1
It's a dual isolated programmable DC power supply, but it has remote
sense and a paralleling relay, which complicate life. We don't know
what bizarre loads the user will have, or if they will connect the
remote sense right.
Sims run super slow and there are many cases to test, so we set up
three monster PCs in the conference room as a simulator farm, to
supplement the two we will use in engineers offices.
Thanks.
Compensating feedback systems to cope with wide ranging capacitive loads
is awkward. I have good results with Phil Perkins stacked RC 3dB/octave
method.
piglet
We have half-bridge switchers followed by multistage LC filters, and
we take the loop-dominant AC feedback early in the filter, with slow
DC feedback from local or remote sensed final output. If users want to
trash their own transient response, let'em. The use loads could even
be negative resistances.

There are self-tuning control systems that learn the overall loop
dynamics and optimize the loop. Or there were; maybe it was a fad. But
that would be a gigantic amount of software to try.

My favorite feed back loop starts at the mosfet switch node, before
any filtering. The transfer function from PWM to switcher voltage is
dimensionless +48 (ignoring the switching, of course.)
Edward Rawde
2024-05-11 22:18:48 UTC
Permalink
Post by John Larkin
Post by piglet
Post by John Larkin
On Fri, 10 May 2024 18:17:47 -0400, "Edward Rawde"
Post by John Larkin
On Thu, 9 May 2024 23:11:03 -0400, "Edward Rawde"
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
Yes, my take is not too far distant but I tried to accomodate the OP's
unexplained desire for ground referenced LED output.
Only one feed wire is needed in a three LED chain if grounded to metalwork.
It's true that most things aren't done like that any more so I don't mind
two wires if it can't be done any other way.
Also two wires might radiate more than one wire, or might not depending on
how they are filtered.
Post by John Larkin
That's nice. It's only an LED, so it probably doesn't need +12v
compensation.
LEDs lose light as temperature rises, so it probably doesn't need Vbe
temp compensation either. I'm glad that you saw the hysteresis trick,
and that you drew a decent looking schematic with a title, date, and
author.
I already knew that most schematics were hideous messes when I read this.
https://worldradiohistory.com/UK/Wireless-World/70s/Wireless-World-1974-11.pdf
Page 451 (pdf page 85)
Perhaps I should have posted the circuit at the top of page 453 and asked
for comments.
Post by John Larkin
We have one project here that has had three or four project engineers
so far, and the project folder contains 175 (yes, 175!) .asc files,
most of which are hideous uncommented messes.
The project folder doesn't have subfolders?

Edit, simulate, edit ,simulate... encourages that.
Just like compile, test, compile test...
Today's world often doesn't allow time for the final design to have its
layout cleaned up whether it's hardware or software.
Time is money.
Post by John Larkin
My sim will be # 176.
https://www.dropbox.com/scl/fi/i1rmnne2j2f2nhetfg1dn/P941C_May11.jpg?rlkey=9by4bmkzo6iim763468y21ko2&raw=1
It's a dual isolated programmable DC power supply, but it has remote
sense and a paralleling relay, which complicate life. We don't know
what bizarre loads the user will have, or if they will connect the
remote sense right.
I'd put that in the spec. Must cope with any kind of bizzare load and remote
sense connected to AC power line.
Ok bizzare load might need further explanation.
Post by John Larkin
Sims run super slow and there are many cases to test, so we set up
three monster PCs in the conference room as a simulator farm, to
supplement the two we will use in engineers offices.
Sounds fine to me but why put them in the conference room when remote
desktop allows access from any computer in the building (or even outside the
building if you know what you're doing with a firewall). I'm currently not
at the location of the computer which will post this.
Edward Rawde
2024-05-11 22:37:21 UTC
Permalink
Post by John Larkin
On Fri, 10 May 2024 18:17:47 -0400, "Edward Rawde"
Post by John Larkin
On Thu, 9 May 2024 23:11:03 -0400, "Edward Rawde"
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
...
Post by John Larkin
Something like this should work.
https://www.dropbox.com/scl/fi/su03d8gaxbi67zhufz3th/LED_CC_Reg_1.jpg?rlkey=oh4ib9011ee1c74ih7hk7dzcb&raw=1
But I'd rather use a TPS562208, which would be cheaper and simpler and
has spread-spectrum to help the EMC thing by about 20 dB.
Thanks for circuit and the chip reference John. That meets my cost
requirement.
I always felt that spread spectrum for EMC was cheating but I'm aware that
there are good arguments why it is not.

Also many thanks to piglet for taking time to post circuits.
John Larkin
2024-05-10 21:06:44 UTC
Permalink
On Fri, 10 May 2024 11:35:35 -0700, John Larkin
Post by John Larkin
On Thu, 9 May 2024 23:11:03 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
Startup behaviour is not ideal but maybe that can be fixed if it needs
fixing.
What's the cheapest op amp I can use for U2 instead of OP07?
Is there a cheaper comparator instead of LT1719 which will work?
Also the fet is bigger than it needs to ne.
Is there a better device for D4? Particularly if R4 can be reduced.
Will it work at all? Except in simulation.
I think I've answered my own question for the current controller but I don't
think it's feasible to attempt a discrete comparator on cost grounds.
I think the LED constant-current switcher can be done with a pfet and
two NPN transistors.
That's overkill. A pfet and one NPN might work.
bitrex
2024-05-10 22:20:39 UTC
Permalink
Post by John Larkin
On Fri, 10 May 2024 11:35:35 -0700, John Larkin
Post by John Larkin
On Thu, 9 May 2024 23:11:03 -0400, "Edward Rawde"
Post by Edward Rawde
Post by Edward Rawde
Now with 9V to 15V input range, direct gate drive and 500mA LED current.
Startup behaviour is not ideal but maybe that can be fixed if it needs
fixing.
What's the cheapest op amp I can use for U2 instead of OP07?
Is there a cheaper comparator instead of LT1719 which will work?
Also the fet is bigger than it needs to ne.
Is there a better device for D4? Particularly if R4 can be reduced.
Will it work at all? Except in simulation.
I think I've answered my own question for the current controller but I don't
think it's feasible to attempt a discrete comparator on cost grounds.
I think the LED constant-current switcher can be done with a pfet and
two NPN transistors.
That's overkill. A pfet and one NPN might work.
Speaking of overkill, wrt our previous discussion you might be
interested in this mixed-signal array that has 8(!) LDOs on board:

<https://www.renesas.com/us/en/products/power-management/multi-channel-power-management-ics-pmics/slg51000-high-psrr-low-noise-multi-output-ldo-ic-advanced-camera-and-sensor-systems#overview>
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