Discussion:
tiny dc/dc
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john larkin
2025-03-27 21:19:18 UTC
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Check out UCC33420.

It's a tiny cheap isolated dc/dc converter. It switches at 64 MHz!
bitrex
2025-03-28 01:41:30 UTC
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Post by john larkin
Check out UCC33420.
It's a tiny cheap isolated dc/dc converter. It switches at 64 MHz!
MSL 3 so buy them in onesies and twosies if you're going to prototype
perhaps.. my experience is that chips with internal isolation barriers
are very sensitive if they get waterlogged, not just reflow but even hot
air or hand soldering may wreck them if they've sat out too long.
john larkin
2025-03-28 02:26:52 UTC
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Post by bitrex
Post by john larkin
Check out UCC33420.
It's a tiny cheap isolated dc/dc converter. It switches at 64 MHz!
MSL 3 so buy them in onesies and twosies if you're going to prototype
perhaps.. my experience is that chips with internal isolation barriers
are very sensitive if they get waterlogged, not just reflow but even hot
air or hand soldering may wreck them if they've sat out too long.
I asked our TI rep for the eval board and he sent me a long list of
questions that I must answer first. Too much hassle, so I'll use a
Murata part.
Phil Hobbs
2025-03-28 04:13:52 UTC
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Post by john larkin
Check out UCC33420.
It's a tiny cheap isolated dc/dc converter. It switches at 64 MHz!
Potentially very nice part, thanks!

Cheers

Phil Hobbs
--
Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC /
Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics
Martin Rid
2025-03-28 20:49:23 UTC
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Check out UCC33420. It's a tiny cheap isolated dc/dc converter. It switches at 64 MHz!
Why does it have such poor esd ratings?
The ucc33421 is better, but not 15kv.
Cheers
--
----Android NewsGroup Reader----
https://piaohong.s3-us-west-2.amazonaws.com/usenet/index.html
john larkin
2025-03-28 22:25:43 UTC
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On Fri, 28 Mar 2025 16:49:23 -0400 (EDT), Martin Rid
Post by Martin Rid
Check out UCC33420. It's a tiny cheap isolated dc/dc converter. It switches at 64 MHz!
Why does it have such poor esd ratings?
The ucc33421 is better, but not 15kv.
Cheers
Right now I dodn't need kilovolts of isolation. I want to make a GaN
totem-pole driver and want a floating power supply for the high side,
but I want very low switching noise for low jitter on the rising edge.

I might try one of these with a bunch of added filtering. It might be
better than some dc/dc that works in the 100 KHz sort of ballpark.

Or it might be much worse.
Bill Sloman
2025-03-29 13:51:36 UTC
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Post by john larkin
On Fri, 28 Mar 2025 16:49:23 -0400 (EDT), Martin Rid
Post by Martin Rid
Check out UCC33420. It's a tiny cheap isolated dc/dc converter. It switches at 64 MHz!
Why does it have such poor esd ratings?
The ucc33421 is better, but not 15kv.
Cheers
Right now I dodn't need kilovolts of isolation. I want to make a GaN
totem-pole driver and want a floating power supply for the high side,
but I want very low switching noise for low jitter on the rising edge.
I might try one of these with a bunch of added filtering. It might be
better than some dc/dc that works in the 100 KHz sort of ballpark.
Or it might be much worse.
The obvious difference is the operating frequency. If you were
particularly worried by 64MHz noise, the high frequency part might
present a problem. With a particularly skilled designer, it might not.

Why not buy one and find out?

--
Bill Sloman, Sydney
Phil Hobbs
2025-03-29 16:30:23 UTC
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Post by john larkin
On Fri, 28 Mar 2025 16:49:23 -0400 (EDT), Martin Rid
Post by Martin Rid
Check out UCC33420. It's a tiny cheap isolated dc/dc converter. It switches at 64 MHz!
Why does it have such poor esd ratings?
The ucc33421 is better, but not 15kv.
Cheers
Right now I dodn't need kilovolts of isolation. I want to make a GaN
totem-pole driver and want a floating power supply for the high side,
but I want very low switching noise for low jitter on the rising edge.
I might try one of these with a bunch of added filtering. It might be
better than some dc/dc that works in the 100 KHz sort of ballpark.
Or it might be much worse.
I bet the gain bandwidth of a GaN FET in its linear range at high current
is pretty impressive.

I’m using SiGe BJTs to speed up the edges of my TDR pulse generators.
Driven from a 500-ps comparator edge, it’s fast enough to oscillate on the
falling edge if the layout isn’t right. That’ll make really entertaining
jitter.

Cheers 🍻

Phil Hobbs
--
Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC /
Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics
john larkin
2025-03-29 17:10:12 UTC
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On Sat, 29 Mar 2025 16:30:23 -0000 (UTC), Phil Hobbs
Post by Phil Hobbs
Post by john larkin
On Fri, 28 Mar 2025 16:49:23 -0400 (EDT), Martin Rid
Post by Martin Rid
Check out UCC33420. It's a tiny cheap isolated dc/dc converter. It switches at 64 MHz!
Why does it have such poor esd ratings?
The ucc33421 is better, but not 15kv.
Cheers
Right now I dodn't need kilovolts of isolation. I want to make a GaN
totem-pole driver and want a floating power supply for the high side,
but I want very low switching noise for low jitter on the rising edge.
I might try one of these with a bunch of added filtering. It might be
better than some dc/dc that works in the 100 KHz sort of ballpark.
Or it might be much worse.
I bet the gain bandwidth of a GaN FET in its linear range at high current
is pretty impressive.
I’m using SiGe BJTs to speed up the edges of my TDR pulse generators.
Driven from a 500-ps comparator edge, it’s fast enough to oscillate on the
falling edge if the layout isn’t right. That’ll make really entertaining
jitter.
Cheers ?
Phil Hobbs
One part that I like is the EPC2037, the tiny BGA thing. I think you
have used it too.

Transconductance is about 1.5S and it's on hard by 3 volts on the
gate. Capacitances are absurdly low compared to a silicon mosfet...
reverse transfer is 0.1 pF.

But a little noise on the gate drive will surely jitter the output.

I never had much luck getting bipolars to make fast output edges, but
I haven't tried SiGe.

That tiny EPC thing is rated for 100 volts and can conduct 2 amps!
Phil Hobbs
2025-03-29 20:22:48 UTC
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Post by john larkin
On Sat, 29 Mar 2025 16:30:23 -0000 (UTC), Phil Hobbs
Post by Phil Hobbs
Post by john larkin
On Fri, 28 Mar 2025 16:49:23 -0400 (EDT), Martin Rid
Post by Martin Rid
Check out UCC33420. It's a tiny cheap isolated dc/dc converter. It switches at 64 MHz!
Why does it have such poor esd ratings?
The ucc33421 is better, but not 15kv.
Cheers
Right now I dodn't need kilovolts of isolation. I want to make a GaN
totem-pole driver and want a floating power supply for the high side,
but I want very low switching noise for low jitter on the rising edge.
I might try one of these with a bunch of added filtering. It might be
better than some dc/dc that works in the 100 KHz sort of ballpark.
Or it might be much worse.
I bet the gain bandwidth of a GaN FET in its linear range at high current
is pretty impressive.
I’m using SiGe BJTs to speed up the edges of my TDR pulse generators.
Driven from a 500-ps comparator edge, it’s fast enough to oscillate on the
falling edge if the layout isn’t right. That’ll make really entertaining
jitter.
Cheers ?
Phil Hobbs
One part that I like is the EPC2037, the tiny BGA thing. I think you
have used it too.
Transconductance is about 1.5S and it's on hard by 3 volts on the
gate. Capacitances are absurdly low compared to a silicon mosfet...
reverse transfer is 0.1 pF.
But a little noise on the gate drive will surely jitter the output.
I never had much luck getting bipolars to make fast output edges, but
I haven't tried SiGe.
I get about 30-40 ps falling edges, which are all that matter for TDR. The
rising edges aren’t nearly as good, because I’m saturating the poor thing
completely. It’s a 65 GHz transistor, though, so even an edge like that
has room for a snivet.
Post by john larkin
That tiny EPC thing is rated for 100 volts and can conduct 2 amps!
Yup, a very nice part. I use it in my ultrafast temperature controller,
which I call a thermal Faraday shield. 🛡️ (Details forthcoming when the
patent gets filed.)

Cheers

Phil Hobbs
--
Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC /
Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics
john larkin
2025-03-29 21:43:06 UTC
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On Sat, 29 Mar 2025 20:22:48 -0000 (UTC), Phil Hobbs
Post by Phil Hobbs
Post by john larkin
On Sat, 29 Mar 2025 16:30:23 -0000 (UTC), Phil Hobbs
Post by Phil Hobbs
Post by john larkin
On Fri, 28 Mar 2025 16:49:23 -0400 (EDT), Martin Rid
Post by Martin Rid
Check out UCC33420. It's a tiny cheap isolated dc/dc converter. It switches at 64 MHz!
Why does it have such poor esd ratings?
The ucc33421 is better, but not 15kv.
Cheers
Right now I dodn't need kilovolts of isolation. I want to make a GaN
totem-pole driver and want a floating power supply for the high side,
but I want very low switching noise for low jitter on the rising edge.
I might try one of these with a bunch of added filtering. It might be
better than some dc/dc that works in the 100 KHz sort of ballpark.
Or it might be much worse.
I bet the gain bandwidth of a GaN FET in its linear range at high current
is pretty impressive.
I?m using SiGe BJTs to speed up the edges of my TDR pulse generators.
Driven from a 500-ps comparator edge, it?s fast enough to oscillate on the
falling edge if the layout isn?t right. That?ll make really entertaining
jitter.
Cheers ?
Phil Hobbs
One part that I like is the EPC2037, the tiny BGA thing. I think you
have used it too.
Transconductance is about 1.5S and it's on hard by 3 volts on the
gate. Capacitances are absurdly low compared to a silicon mosfet...
reverse transfer is 0.1 pF.
But a little noise on the gate drive will surely jitter the output.
I never had much luck getting bipolars to make fast output edges, but
I haven't tried SiGe.
I get about 30-40 ps falling edges, which are all that matter for TDR. The
rising edges aren’t nearly as good, because I’m saturating the poor thing
completely. It’s a 65 GHz transistor, though, so even an edge like that
has room for a snivet.
Post by john larkin
That tiny EPC thing is rated for 100 volts and can conduct 2 amps!
Yup, a very nice part. I use it in my ultrafast temperature controller,
which I call a thermal Faraday shield. ?? (Details forthcoming when the
patent gets filed.)
Cheers
Phil Hobbs
I use the 2037 and 2038 in the output stage of our DDG

https://highlandtechnology.com/Product/P500

which was a lot of work.
Phil Hobbs
2025-03-29 21:49:56 UTC
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Post by john larkin
On Sat, 29 Mar 2025 20:22:48 -0000 (UTC), Phil Hobbs
Post by Phil Hobbs
Post by john larkin
On Sat, 29 Mar 2025 16:30:23 -0000 (UTC), Phil Hobbs
Post by Phil Hobbs
Post by john larkin
On Fri, 28 Mar 2025 16:49:23 -0400 (EDT), Martin Rid
Post by Martin Rid
Check out UCC33420. It's a tiny cheap isolated dc/dc converter. It
switches at 64 MHz!
Why does it have such poor esd ratings?
The ucc33421 is better, but not 15kv.
Cheers
Right now I dodn't need kilovolts of isolation. I want to make a GaN
totem-pole driver and want a floating power supply for the high side,
but I want very low switching noise for low jitter on the rising edge.
I might try one of these with a bunch of added filtering. It might be
better than some dc/dc that works in the 100 KHz sort of ballpark.
Or it might be much worse.
I bet the gain bandwidth of a GaN FET in its linear range at high current
is pretty impressive.
I?m using SiGe BJTs to speed up the edges of my TDR pulse generators.
Driven from a 500-ps comparator edge, it?s fast enough to oscillate on the
falling edge if the layout isn?t right. That?ll make really entertaining
jitter.
Cheers ?
Phil Hobbs
One part that I like is the EPC2037, the tiny BGA thing. I think you
have used it too.
Transconductance is about 1.5S and it's on hard by 3 volts on the
gate. Capacitances are absurdly low compared to a silicon mosfet...
reverse transfer is 0.1 pF.
But a little noise on the gate drive will surely jitter the output.
I never had much luck getting bipolars to make fast output edges, but
I haven't tried SiGe.
I get about 30-40 ps falling edges, which are all that matter for TDR. The
rising edges aren’t nearly as good, because I’m saturating the poor thing
completely. It’s a 65 GHz transistor, though, so even an edge like that
has room for a snivet.
Post by john larkin
That tiny EPC thing is rated for 100 volts and can conduct 2 amps!
Yup, a very nice part. I use it in my ultrafast temperature controller,
which I call a thermal Faraday shield. ?? (Details forthcoming when the
patent gets filed.)
Cheers
Phil Hobbs
I use the 2037 and 2038 in the output stage of our DDG
https://highlandtechnology.com/Product/P500
which was a lot of work.
I believe that. Did you get one for your bench?

Cheers

Phil Hobbs
--
Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC /
Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics
john larkin
2025-03-30 01:55:45 UTC
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On Sat, 29 Mar 2025 21:49:56 -0000 (UTC), Phil Hobbs
Post by Phil Hobbs
Post by john larkin
On Sat, 29 Mar 2025 20:22:48 -0000 (UTC), Phil Hobbs
Post by Phil Hobbs
Post by john larkin
On Sat, 29 Mar 2025 16:30:23 -0000 (UTC), Phil Hobbs
Post by Phil Hobbs
Post by john larkin
On Fri, 28 Mar 2025 16:49:23 -0400 (EDT), Martin Rid
Post by Martin Rid
Check out UCC33420. It's a tiny cheap isolated dc/dc converter. It
switches at 64 MHz!
Why does it have such poor esd ratings?
The ucc33421 is better, but not 15kv.
Cheers
Right now I dodn't need kilovolts of isolation. I want to make a GaN
totem-pole driver and want a floating power supply for the high side,
but I want very low switching noise for low jitter on the rising edge.
I might try one of these with a bunch of added filtering. It might be
better than some dc/dc that works in the 100 KHz sort of ballpark.
Or it might be much worse.
I bet the gain bandwidth of a GaN FET in its linear range at high current
is pretty impressive.
I?m using SiGe BJTs to speed up the edges of my TDR pulse generators.
Driven from a 500-ps comparator edge, it?s fast enough to oscillate on the
falling edge if the layout isn?t right. That?ll make really entertaining
jitter.
Cheers ?
Phil Hobbs
One part that I like is the EPC2037, the tiny BGA thing. I think you
have used it too.
Transconductance is about 1.5S and it's on hard by 3 volts on the
gate. Capacitances are absurdly low compared to a silicon mosfet...
reverse transfer is 0.1 pF.
But a little noise on the gate drive will surely jitter the output.
I never had much luck getting bipolars to make fast output edges, but
I haven't tried SiGe.
I get about 30-40 ps falling edges, which are all that matter for TDR. The
rising edges aren?t nearly as good, because I?m saturating the poor thing
completely. It?s a 65 GHz transistor, though, so even an edge like that
has room for a snivet.
Post by john larkin
That tiny EPC thing is rated for 100 volts and can conduct 2 amps!
Yup, a very nice part. I use it in my ultrafast temperature controller,
which I call a thermal Faraday shield. ?? (Details forthcoming when the
patent gets filed.)
Cheers
Phil Hobbs
I use the 2037 and 2038 in the output stage of our DDG
https://highlandtechnology.com/Product/P500
which was a lot of work.
I believe that. Did you get one for your bench?
Cheers
Phil Hobbs
Yes!

Did you get your old dead P400 repaired? Do you have two now?

People tell me that the old P400s have less jitter than the new P500.
I suspect that dc/dc converter noise in the P500 output stage is the
culprit, and the TI dc/dc might fix that.
legg
2025-03-29 14:47:14 UTC
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On Fri, 28 Mar 2025 16:49:23 -0400 (EDT), Martin Rid
Post by Martin Rid
Check out UCC33420. It's a tiny cheap isolated dc/dc converter. It switches at 64 MHz!
Why does it have such poor esd ratings?
The ucc33421 is better, but not 15kv.
Cheers
It doesn't actually have an ESD rating - spec only mentions the
relevant standards and advises care in layout.

Those are isolation test voltages you`re looking at.

RL
Sylvia Else
2025-03-30 04:40:08 UTC
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Post by john larkin
Check out UCC33420.
It's a tiny cheap isolated dc/dc converter. It switches at 64 MHz!
I note that most have basic isolation, but a couple have reinforced
isolation.

So, how long before Chinese fraudsters start relabeling the presumably
cheaper basic isolation models as more expensive reinforced isolation parts?

Sylvia.
Uwe Bonnes
2025-03-30 21:43:28 UTC
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Post by john larkin
Check out UCC33420.
It's a tiny cheap isolated dc/dc converter. It switches at 64 MHz!
I guess Murata NXJ switches at a similar frequency!
--
Uwe Bonnes ***@elektron.ikp.physik.tu-darmstadt.de

Institut fuer Kernphysik Schlossgartenstrasse 9 64289 Darmstadt
--------- Tel. 06151 1623569 ------- Fax. 06151 1623305 ---------
john larkin
2025-03-30 23:37:46 UTC
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On 30 Mar 2025 21:43:28 GMT, Uwe Bonnes
Post by Uwe Bonnes
Post by john larkin
Check out UCC33420.
It's a tiny cheap isolated dc/dc converter. It switches at 64 MHz!
I guess Murata NXJ switches at a similar frequency!
About 100 KHz.

https://www.dropbox.com/scl/fo/w90gg474w9h0wsqkbpd9e/AC8Oh-LB9La9PcvIGGOYWtg?rlkey=agwx067u5vk6z04ir2ktp4dy0&dl=0
Uwe Bonnes
2025-04-01 12:49:38 UTC
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Post by john larkin
On 30 Mar 2025 21:43:28 GMT, Uwe Bonnes
Post by Uwe Bonnes
Post by john larkin
Check out UCC33420.
It's a tiny cheap isolated dc/dc converter. It switches at 64 MHz!
I guess Murata NXJ switches at a similar frequency!
About 100 KHz.
https://www.dropbox.com/scl/fo/w90gg474w9h0wsqkbpd9e/AC8Oh-LB9La9PcvIGGOYWtg?rlkey=agwx067u5vk6z04ir2ktp4dy0&dl=0
Thanks!
--
Uwe Bonnes ***@elektron.ikp.physik.tu-darmstadt.de

Institut fuer Kernphysik Schlossgartenstrasse 9 64289 Darmstadt
--------- Tel. 06151 1623569 ------- Fax. 06151 1623305 ---------
Uwe Bonnes
2025-04-01 12:50:07 UTC
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Post by john larkin
On 30 Mar 2025 21:43:28 GMT, Uwe Bonnes
Post by Uwe Bonnes
Post by john larkin
Check out UCC33420.
It's a tiny cheap isolated dc/dc converter. It switches at 64 MHz!
I guess Murata NXJ switches at a similar frequency!
About 100 KHz.
...
And MPS MIE1Wxx?
--
Uwe Bonnes ***@elektron.ikp.physik.tu-darmstadt.de

Institut fuer Kernphysik Schlossgartenstrasse 9 64289 Darmstadt
--------- Tel. 06151 1623569 ------- Fax. 06151 1623305 ---------
john larkin
2025-04-01 17:30:07 UTC
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On 1 Apr 2025 12:50:07 GMT, Uwe Bonnes
Post by Uwe Bonnes
Post by john larkin
On 30 Mar 2025 21:43:28 GMT, Uwe Bonnes
Post by Uwe Bonnes
Post by john larkin
Check out UCC33420.
It's a tiny cheap isolated dc/dc converter. It switches at 64 MHz!
I guess Murata NXJ switches at a similar frequency!
About 100 KHz.
...
And MPS MIE1Wxx?
Do you use that one? It looks tiny, cheap, noisy, and inefficient but
would be fine for many uses. It would be interesting to x-ray.

By the reel, it's 89 cents!

john larkin
2025-04-01 02:38:55 UTC
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Post by john larkin
Check out UCC33420.
It's a tiny cheap isolated dc/dc converter. It switches at 64 MHz!
What I need is a photovoltaic optocoupler with serious CTR. The ones I
can get have CTRs like 0.5%. Power gain is better, but they make 8 or
so volts and I only need 3.3.

I recall someone once making some optocouplers with serious power
capability, but can't find them now.

A PV would sure be quiet.
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