One of our customers returned a bunch of fried VME waveform generators

http://www.highlandtechnology.com/DSS/V375DS.shtml

They were installed in a VME crate that has a kinda clumsy push-push
power switch. If you fumble with it just right, turn if off for about
3/4 of a second and turn it back on, the +5 bus spikes to about +9.

Our modules don't like that. Some of the older FPGAs are powered
directly from +5.

So I've volunteered to make a clamp module. I'm thinking about three
or four 1000 watt, 1000 amp mosfets and some sort of gate driver.

IXFH400N075 maybe.

If I make a VME module and use the P1 and P2 connectors, I'll have six
pins for the +5.

Anybody want to have a whack at the gate driver circuit?

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

jlarkin@highlandsniptechnology.com wrote:
> One of our customers returned a bunch of fried VME waveform generators
>
> http://www.highlandtechnology.com/DSS/V375DS.shtml
>
> They were installed in a VME crate that has a kinda clumsy push-push
> power switch. If you fumble with it just right, turn if off for about
> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
>
> Our modules don't like that. Some of the older FPGAs are powered
> directly from +5.
>
> So I've volunteered to make a clamp module. I'm thinking about three
> or four 1000 watt, 1000 amp mosfets and some sort of gate driver.
>
> IXFH400N075 maybe.
>
> If I make a VME module and use the P1 and P2 connectors, I'll have six
> pins for the +5.
>
> Anybody want to have a whack at the gate driver circuit?

why not just get power supplies that don't suck?

On Saturday, June 5, 2021 at 4:23:26 PM UTC-4, jla...@highlandsniptechnology.com wrote:
> One of our customers returned a bunch of fried VME waveform generators
>
> http://www.highlandtechnology.com/DSS/V375DS.shtml
>
> They were installed in a VME crate that has a kinda clumsy push-push
> power switch. If you fumble with it just right, turn if off for about
> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.

How the hell does that happen???

>
> Our modules don't like that. Some of the older FPGAs are powered
> directly from +5.
>
> So I've volunteered to make a clamp module. I'm thinking about three
> or four 1000 watt, 1000 amp mosfets and some sort of gate driver.
>
> IXFH400N075 maybe.
>
> If I make a VME module and use the P1 and P2 connectors, I'll have six
> pins for the +5.
>
> Anybody want to have a whack at the gate driver circuit?
>
>
>
> --
>
> John Larkin Highland Technology, Inc
>
> The best designs are necessarily accidental.

On Saturday, June 5, 2021 at 4:23:26 PM UTC-4, jla...@highlandsniptechnology.com wrote:
> One of our customers returned a bunch of fried VME waveform generators
>
> http://www.highlandtechnology.com/DSS/V375DS.shtml
>
> They were installed in a VME crate that has a kinda clumsy push-push
> power switch. If you fumble with it just right, turn if off for about
> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
>
> Our modules don't like that. Some of the older FPGAs are powered
> directly from +5.
>
> So I've volunteered to make a clamp module. I'm thinking about three
> or four 1000 watt, 1000 amp mosfets and some sort of gate driver.

Don't do that. Put a delay-on-break relay in line with the mains. It won't let power be re-applied for the timeout etc...

>
> IXFH400N075 maybe.
>
> If I make a VME module and use the P1 and P2 connectors, I'll have six
> pins for the +5.
>
> Anybody want to have a whack at the gate driver circuit?
>
>
>
> --
>
> John Larkin Highland Technology, Inc
>
> The best designs are necessarily accidental.

On Saturday, June 5, 2021 at 4:23:26 PM UTC-4, jla...@highlandsniptechnology.com wrote:
> One of our customers returned a bunch of fried VME waveform generators
>
> http://www.highlandtechnology.com/DSS/V375DS.shtml
>
> They were installed in a VME crate that has a kinda clumsy push-push
> power switch. If you fumble with it just right, turn if off for about
> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
>
> Our modules don't like that. Some of the older FPGAs are powered
> directly from +5.
>
> So I've volunteered to make a clamp module. I'm thinking about three
> or four 1000 watt, 1000 amp mosfets and some sort of gate driver.
>
> IXFH400N075 maybe.
>
> If I make a VME module and use the P1 and P2 connectors, I'll have six
> pins for the +5.
>
> Anybody want to have a whack at the gate driver circuit?

I should add the delay-on-break will not interfere with normal operation. E.g., if the power has been off for the timeout duration, as when the crate has been off normally, it will allow the power to come right up without delay.

>
>
>
> --
>
> John Larkin Highland Technology, Inc
>
> The best designs are necessarily accidental.

On 6/5/2021 1:23 PM, jlarkin@highlandsniptechnology.com wrote:
> One of our customers returned a bunch of fried VME waveform generators
>
> http://www.highlandtechnology.com/DSS/V375DS.shtml
>
> They were installed in a VME crate that has a kinda clumsy push-push
> power switch. If you fumble with it just right, turn if off for about
> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
>
> Our modules don't like that. Some of the older FPGAs are powered
> directly from +5.
>
> So I've volunteered to make a clamp module. I'm thinking about three
> or four 1000 watt, 1000 amp mosfets and some sort of gate driver.
>
> IXFH400N075 maybe.
>
> If I make a VME module and use the P1 and P2 connectors, I'll have six
> pins for the +5.
>
> Anybody want to have a whack at the gate driver circuit?

Seems like it would be easier to just bolt on a "switch smartenerupper"
to ensure power never gets cycled in ways that upset the power supplies.

Don Y wrote:
> On 6/5/2021 1:23 PM, jlarkin@highlandsniptechnology.com wrote:
>> One of our customers returned a bunch of fried VME waveform
>> generators http://www.highlandtechnology.com/DSS/V375DS.shtml
>>
>> They were installed in a VME crate that has a kinda clumsy push-push
>> power switch. If you fumble with it just right, turn if off for about
>> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
>>
>> Our modules don't like that. Some of the older FPGAs are powered
>> directly from +5.
>>
>> So I've volunteered to make a clamp module. I'm thinking about three
>> or four 1000 watt, 1000 amp mosfets and some sort of gate driver.
>>
>> IXFH400N075 maybe.
>>
>> If I make a VME module and use the P1 and P2 connectors, I'll have
>> six pins for the +5.
>>
>> Anybody want to have a whack at the gate driver circuit?
>
> Seems like it would be easier to just bolt on a "switch
> smartenerupper" to ensure power never gets cycled in ways that upset
> the power supplies.

Yeah, I'm an amateur hobbyist know-nothing, but I would think an OVP
should be inside the supply, not plugged into the bus. If you need four
1000 amp MOSFET's then won't there be some drop along the backplane
which would cause another board to get 7 or 8 volts? And what about
would it do to the connector? Oxidation? Melting?

--
Defund the Thought Police

On 6/5/2021 2:09 PM, Fred Bloggs wrote:
> On Saturday, June 5, 2021 at 4:23:26 PM UTC-4,
> jla...@highlandsniptechnology.com wrote:
>> One of our customers returned a bunch of fried VME waveform generators
>>
>> http://www.highlandtechnology.com/DSS/V375DS.shtml
>>
>> They were installed in a VME crate that has a kinda clumsy push-push power
>> switch. If you fumble with it just right, turn if off for about 3/4 of a
>> second and turn it back on, the +5 bus spikes to about +9.
>>
>> Our modules don't like that. Some of the older FPGAs are powered directly
>> from +5.
>>
>> So I've volunteered to make a clamp module. I'm thinking about three or
>> four 1000 watt, 1000 amp mosfets and some sort of gate driver.
>
> Don't do that. Put a delay-on-break relay in line with the mains. It won't
> let power be re-applied for the timeout etc...

"Time" is likely a second-order manifestation. You likely want to watch
some (or all) of the supplies and ensure they have discharged to some
"appropriate" level before allowing power to be reapplied.

Note that how quickly the supplies discharge will likely be reflective
of the actual load they are PRESENTLY seeing. So, the "time" could
change if the loading on the backplane changed (e.g., if one or more
modules were removed).

Using the current state of the supplies is more consistent with
<whatever> is causing them to misbehave in this short-cycled
application.

On Sat, 5 Jun 2021 20:38:11 +0000 (UTC), Cydrome Leader
<presence@MUNGEpanix.com> wrote:

>jlarkin@highlandsniptechnology.com wrote:
>> One of our customers returned a bunch of fried VME waveform generators
>>
>> http://www.highlandtechnology.com/DSS/V375DS.shtml
>>
>> They were installed in a VME crate that has a kinda clumsy push-push
>> power switch. If you fumble with it just right, turn if off for about
>> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
>>
>> Our modules don't like that. Some of the older FPGAs are powered
>> directly from +5.
>>
>> So I've volunteered to make a clamp module. I'm thinking about three
>> or four 1000 watt, 1000 amp mosfets and some sort of gate driver.
>>
>> IXFH400N075 maybe.
>>
>> If I make a VME module and use the P1 and P2 connectors, I'll have six
>> pins for the +5.
>>
>> Anybody want to have a whack at the gate driver circuit?
>
>why not just get power supplies that don't suck?

That's not my call.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

On Sat, 5 Jun 2021 13:38:55 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:

>On Saturday, June 5, 2021 at 4:23:26 PM UTC-4, jla...@highlandsniptechnology.com wrote:
>> One of our customers returned a bunch of fried VME waveform generators
>>
>> http://www.highlandtechnology.com/DSS/V375DS.shtml
>>
>> They were installed in a VME crate that has a kinda clumsy push-push
>> power switch. If you fumble with it just right, turn if off for about
>> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
>
>How the hell does that happen???

Looks like someone bought some switching supplies and hacked into them
to add a low current pushbutton power switch on the front panel.
Badly.

If I fix them, maybe for free, I'll make some friends.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

On Sat, 5 Jun 2021 14:09:29 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:

>On Saturday, June 5, 2021 at 4:23:26 PM UTC-4, jla...@highlandsniptechnology.com wrote:
>> One of our customers returned a bunch of fried VME waveform generators
>>
>> http://www.highlandtechnology.com/DSS/V375DS.shtml
>>
>> They were installed in a VME crate that has a kinda clumsy push-push
>> power switch. If you fumble with it just right, turn if off for about
>> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
>>
>> Our modules don't like that. Some of the older FPGAs are powered
>> directly from +5.
>>
>> So I've volunteered to make a clamp module. I'm thinking about three
>> or four 1000 watt, 1000 amp mosfets and some sort of gate driver.
>
>Don't do that. Put a delay-on-break relay in line with the mains. It won't let power be re-applied for the timeout etc...
>
>

It would be a major project to remove all the crates from a bunch of
sites and add all that stuff. A plugin clamp would be an easy field
addition.

Looks like 10 or so surface-mount dpak fets would be nice. We have
FDD86367 in stock. Each will conduct about 100 amps with 5.5v on the
gate.

Nobody in SED seems to want to actually D.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

On 6/5/2021 2:21 PM, Tom Del Rosso wrote:
> Don Y wrote:
>> On 6/5/2021 1:23 PM, jlarkin@highlandsniptechnology.com wrote:
>>> One of our customers returned a bunch of fried VME waveform
>>> generators http://www.highlandtechnology.com/DSS/V375DS.shtml
>>>
>>> They were installed in a VME crate that has a kinda clumsy push-push
>>> power switch. If you fumble with it just right, turn if off for about
>>> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
>>>
>>> Our modules don't like that. Some of the older FPGAs are powered
>>> directly from +5.
>>>
>>> So I've volunteered to make a clamp module. I'm thinking about three
>>> or four 1000 watt, 1000 amp mosfets and some sort of gate driver.
>>>
>>> IXFH400N075 maybe.
>>>
>>> If I make a VME module and use the P1 and P2 connectors, I'll have
>>> six pins for the +5.
>>>
>>> Anybody want to have a whack at the gate driver circuit?
>>
>> Seems like it would be easier to just bolt on a "switch
>> smartenerupper" to ensure power never gets cycled in ways that upset
>> the power supplies.
>
> Yeah, I'm an amateur hobbyist know-nothing, but I would think an OVP
> should be inside the supply, not plugged into the bus. If you need four
> 1000 amp MOSFET's then won't there be some drop along the backplane
> which would cause another board to get 7 or 8 volts? And what about
> would it do to the connector? Oxidation? Melting?

Yeah, seems like a bigger effort with more unknowns than
simply addressing the (apparent) "cause" of the problem.

Like beefing up the bumpers on your car because your
brakes aren't good...

On 6/5/2021 3:02 PM, Don Y wrote:
> On 6/5/2021 2:21 PM, Tom Del Rosso wrote:
>> Don Y wrote:
>>> On 6/5/2021 1:23 PM, jlarkin@highlandsniptechnology.com wrote:
>>>> One of our customers returned a bunch of fried VME waveform
>>>> generators http://www.highlandtechnology.com/DSS/V375DS.shtml
>>>>
>>>> They were installed in a VME crate that has a kinda clumsy push-push
>>>> power switch. If you fumble with it just right, turn if off for about
>>>> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
>>>>
>>>> Our modules don't like that. Some of the older FPGAs are powered
>>>> directly from +5.
>>>>
>>>> So I've volunteered to make a clamp module. I'm thinking about three
>>>> or four 1000 watt, 1000 amp mosfets and some sort of gate driver.
>>>>
>>>> IXFH400N075 maybe.
>>>>
>>>> If I make a VME module and use the P1 and P2 connectors, I'll have
>>>> six pins for the +5.
>>>>
>>>> Anybody want to have a whack at the gate driver circuit?
>>>
>>> Seems like it would be easier to just bolt on a "switch
>>> smartenerupper" to ensure power never gets cycled in ways that upset
>>> the power supplies.
>>
>> Yeah, I'm an amateur hobbyist know-nothing, but I would think an OVP
>> should be inside the supply, not plugged into the bus. If you need four
>> 1000 amp MOSFET's then won't there be some drop along the backplane
>> which would cause another board to get 7 or 8 volts? And what about
>> would it do to the connector? Oxidation? Melting?
>
> Yeah, seems like a bigger effort with more unknowns than
> simply addressing the (apparent) "cause" of the problem.
>
> Like beefing up the bumpers on your car because your
> brakes aren't good...

.... and then discovering that all that abuse has bent the frame!

(so, reinforce the frame with some extra steel...)

On Sat, 05 Jun 2021 14:45:30 -0700, jlarkin@highlandsniptechnology.com
wrote:

>On Sat, 5 Jun 2021 13:38:55 -0700 (PDT), Fred Bloggs
><bloggs.fredbloggs.fred@gmail.com> wrote:
>
>>On Saturday, June 5, 2021 at 4:23:26 PM UTC-4, jla...@highlandsniptechnology.com wrote:
>>> One of our customers returned a bunch of fried VME waveform generators
>>>
>>> http://www.highlandtechnology.com/DSS/V375DS.shtml
>>>
>>> They were installed in a VME crate that has a kinda clumsy push-push
>>> power switch. If you fumble with it just right, turn if off for about
>>> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
>>
>>How the hell does that happen???
>
>Looks like someone bought some switching supplies and hacked into them
>to add a low current pushbutton power switch on the front panel.
>Badly.
>
>If I fix them, maybe for free, I'll make some friends.

Hack into the low power push-botton switch.

There's a bunch of POR detectors with delays in the second range.

PT7M6315 2000ms
MCP130T 700ms
STM6524 4000-7500ms
SR2LA 4000-7500ms

Fighting the overshoot with an active clamp shouldn't be as
power-intensive as you're thinking. a simple to247 doing its
zener clamping to 4VGS + a couple of diode drops should do it.

Do both. Belt and braces.

RL

Don Y <blockedofcourse@foo.invalid> wrote:
> On 6/5/2021 2:21 PM, Tom Del Rosso wrote:
>> Don Y wrote:
>>> On 6/5/2021 1:23 PM, jlarkin@highlandsniptechnology.com wrote:
>>>> One of our customers returned a bunch of fried VME waveform
>>>> generators http://www.highlandtechnology.com/DSS/V375DS.shtml
>>>>
>>>> They were installed in a VME crate that has a kinda clumsy push-push
>>>> power switch. If you fumble with it just right, turn if off for about
>>>> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
>>>>
>>>> Our modules don't like that. Some of the older FPGAs are powered
>>>> directly from +5.
>>>>
>>>> So I've volunteered to make a clamp module. I'm thinking about three
>>>> or four 1000 watt, 1000 amp mosfets and some sort of gate driver.
>>>>
>>>> IXFH400N075 maybe.
>>>>
>>>> If I make a VME module and use the P1 and P2 connectors, I'll have
>>>> six pins for the +5.
>>>>
>>>> Anybody want to have a whack at the gate driver circuit?
>>>
>>> Seems like it would be easier to just bolt on a "switch
>>> smartenerupper" to ensure power never gets cycled in ways that upset
>>> the power supplies.
>>
>> Yeah, I'm an amateur hobbyist know-nothing, but I would think an OVP
>> should be inside the supply, not plugged into the bus. If you need four
>> 1000 amp MOSFET's then won't there be some drop along the backplane
>> which would cause another board to get 7 or 8 volts? And what about
>> would it do to the connector? Oxidation? Melting?
>
> Yeah, seems like a bigger effort with more unknowns than
> simply addressing the (apparent) "cause" of the problem.
>
> Like beefing up the bumpers on your car because your
> brakes aren't good...

yeah, this entire project sounds stupid. It sounds like the repair fees
for the blown cards is pretty low though, so everyone should be happy.

On Saturday, June 5, 2021 at 7:27:04 PM UTC-7, Cydrome Leader wrote:
> Don Y <blocked...@foo.invalid> wrote:
> > On 6/5/2021 2:21 PM, Tom Del Rosso wrote:
> >> Don Y wrote:
> >>> On 6/5/2021 1:23 PM, jla...@highlandsniptechnology.com wrote:
> >>>> One of our customers returned a bunch of fried VME waveform
> >>>> generators http://www.highlandtechnology.com/DSS/V375DS.shtml
> >>>>
> >>>> They were installed in a VME crate that has a kinda clumsy push-push
> >>>> power switch. If you fumble with it just right, turn if off for about
> >>>> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
> >>>>
> >>>> Our modules don't like that. Some of the older FPGAs are powered
> >>>> directly from +5.
> >>>>
> >>>> So I've volunteered to make a clamp module. I'm thinking about three
> >>>> or four 1000 watt, 1000 amp mosfets and some sort of gate driver.
> >>>>
> >>>> IXFH400N075 maybe.
> >>>>
> >>>> If I make a VME module and use the P1 and P2 connectors, I'll have
> >>>> six pins for the +5.
> >>>>
> >>>> Anybody want to have a whack at the gate driver circuit?
> >>>
> >>> Seems like it would be easier to just bolt on a "switch
> >>> smartenerupper" to ensure power never gets cycled in ways that upset
> >>> the power supplies.
> >>
> >> Yeah, I'm an amateur hobbyist know-nothing, but I would think an OVP
> >> should be inside the supply, not plugged into the bus. If you need four
> >> 1000 amp MOSFET's then won't there be some drop along the backplane
> >> which would cause another board to get 7 or 8 volts? And what about
> >> would it do to the connector? Oxidation? Melting?
> >
> > Yeah, seems like a bigger effort with more unknowns than
> > simply addressing the (apparent) "cause" of the problem.
> >
> > Like beefing up the bumpers on your car because your
> > brakes aren't good...
> yeah, this entire project sounds stupid. It sounds like the repair fees
> for the blown cards is pretty low though, so everyone should be happy.
Here are a bunch of SCR crowbar circuits:
https://www.google.com/search?rlz=1C1RXQR_enUS934US934&sxsrf=ALeKk01ShGR6oemCtdKzR0_qkEPgkjA8bg:1622947548395&source=univ&tbm=isch&q=scr+crowbar+voltage+clamp+module+5v&sa=X&ved=2ahUKEwjGr_Hg_oHxAhWGbs0KHcRCAacQjJkEegQIFBAB&biw=1280&bih=625

On Sat, 5 Jun 2021 19:47:16 -0700 (PDT), Flyguy
<soar2morrow@yahoo.com> wrote:

>On Saturday, June 5, 2021 at 7:27:04 PM UTC-7, Cydrome Leader wrote:
>> Don Y <blocked...@foo.invalid> wrote:
>> > On 6/5/2021 2:21 PM, Tom Del Rosso wrote:
>> >> Don Y wrote:
>> >>> On 6/5/2021 1:23 PM, jla...@highlandsniptechnology.com wrote:
>> >>>> One of our customers returned a bunch of fried VME waveform
>> >>>> generators http://www.highlandtechnology.com/DSS/V375DS.shtml
>> >>>>
>> >>>> They were installed in a VME crate that has a kinda clumsy push-push
>> >>>> power switch. If you fumble with it just right, turn if off for about
>> >>>> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
>> >>>>
>> >>>> Our modules don't like that. Some of the older FPGAs are powered
>> >>>> directly from +5.
>> >>>>
>> >>>> So I've volunteered to make a clamp module. I'm thinking about three
>> >>>> or four 1000 watt, 1000 amp mosfets and some sort of gate driver.
>> >>>>
>> >>>> IXFH400N075 maybe.
>> >>>>
>> >>>> If I make a VME module and use the P1 and P2 connectors, I'll have
>> >>>> six pins for the +5.
>> >>>>
>> >>>> Anybody want to have a whack at the gate driver circuit?
>> >>>
>> >>> Seems like it would be easier to just bolt on a "switch
>> >>> smartenerupper" to ensure power never gets cycled in ways that upset
>> >>> the power supplies.
>> >>
>> >> Yeah, I'm an amateur hobbyist know-nothing, but I would think an OVP
>> >> should be inside the supply, not plugged into the bus. If you need four
>> >> 1000 amp MOSFET's then won't there be some drop along the backplane
>> >> which would cause another board to get 7 or 8 volts? And what about
>> >> would it do to the connector? Oxidation? Melting?
>> >
>> > Yeah, seems like a bigger effort with more unknowns than
>> > simply addressing the (apparent) "cause" of the problem.
>> >
>> > Like beefing up the bumpers on your car because your
>> > brakes aren't good...
>> yeah, this entire project sounds stupid. It sounds like the repair fees
>> for the blown cards is pretty low though, so everyone should be happy.
>Here are a bunch of SCR crowbar circuits:
>https://www.google.com/search?rlz=1C1RXQR_enUS934US934&sxsrf=ALeKk01ShGR6oemCtdKzR0_qkEPgkjA8bg:1622947548395&source=univ&tbm=isch&q=scr+crowbar+voltage+clamp+module+5v&sa=X&ved=2ahUKEwjGr_Hg_oHxAhWGbs0KHcRCAacQjJkEegQIFBAB&biw=1280&bih=625

A crowbar would shut down the system. I guess that's better than
blowing up modules, but just working would be even better.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

On Sat, 05 Jun 2021 18:40:03 -0400, legg <legg@nospam.magma.ca> wrote:

>On Sat, 05 Jun 2021 14:45:30 -0700, jlarkin@highlandsniptechnology.com
>wrote:
>
>>On Sat, 5 Jun 2021 13:38:55 -0700 (PDT), Fred Bloggs
>><bloggs.fredbloggs.fred@gmail.com> wrote:
>>
>>>On Saturday, June 5, 2021 at 4:23:26 PM UTC-4, jla...@highlandsniptechnology.com wrote:
>>>> One of our customers returned a bunch of fried VME waveform generators
>>>>
>>>> http://www.highlandtechnology.com/DSS/V375DS.shtml
>>>>
>>>> They were installed in a VME crate that has a kinda clumsy push-push
>>>> power switch. If you fumble with it just right, turn if off for about
>>>> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
>>>
>>>How the hell does that happen???
>>
>>Looks like someone bought some switching supplies and hacked into them
>>to add a low current pushbutton power switch on the front panel.
>>Badly.
>>
>>If I fix them, maybe for free, I'll make some friends.
>
>
>Hack into the low power push-botton switch.
>
>There's a bunch of POR detectors with delays in the second range.
>
>PT7M6315 2000ms
>MCP130T 700ms
>STM6524 4000-7500ms
>SR2LA 4000-7500ms
>
>Fighting the overshoot with an active clamp shouldn't be as
>power-intensive as you're thinking. a simple to247 doing its
>zener clamping to 4VGS + a couple of diode drops should do it.
>
>Do both. Belt and braces.
>
>RL

Pulling the crates and reworking them would be a big deal.

I'm laying out a board now, with ten beefy DPAK fets with a bit of
resistance in the drains to share the dissipation.

Since nobody here wants to discuss the design of a gate driver, I did
it myself.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

On Saturday, June 5, 2021 at 9:02:59 PM UTC-7, jla...@highlandsniptechnology.com wrote:
> On Sat, 05 Jun 2021 18:40:03 -0400, legg <le...@nospam.magma.ca> wrote:
>
> >On Sat, 05 Jun 2021 14:45:30 -0700, jla...@highlandsniptechnology.com
> >wrote:
> >
> >>On Sat, 5 Jun 2021 13:38:55 -0700 (PDT), Fred Bloggs
> >><bloggs.fred...@gmail.com> wrote:
> >>
> >>>On Saturday, June 5, 2021 at 4:23:26 PM UTC-4, jla...@highlandsniptechnology.com wrote:
> >>>> One of our customers returned a bunch of fried VME waveform generators
> >>>>
> >>>> http://www.highlandtechnology.com/DSS/V375DS.shtml
> >>>>
> >>>> They were installed in a VME crate that has a kinda clumsy push-push
> >>>> power switch. If you fumble with it just right, turn if off for about
> >>>> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
> >>>
> >>>How the hell does that happen???
> >>
> >>Looks like someone bought some switching supplies and hacked into them
> >>to add a low current pushbutton power switch on the front panel.
> >>Badly.
> >>
> >>If I fix them, maybe for free, I'll make some friends.
> >
> >
> >Hack into the low power push-botton switch.
> >
> >There's a bunch of POR detectors with delays in the second range.
> >
> >PT7M6315 2000ms
> >MCP130T 700ms
> >STM6524 4000-7500ms
> >SR2LA 4000-7500ms
> >
> >Fighting the overshoot with an active clamp shouldn't be as
> >power-intensive as you're thinking. a simple to247 doing its
> >zener clamping to 4VGS + a couple of diode drops should do it.
> >
> >Do both. Belt and braces.
> >
> >RL
> Pulling the crates and reworking them would be a big deal.
>
> I'm laying out a board now, with ten beefy DPAK fets with a bit of
> resistance in the drains to share the dissipation.
>
> Since nobody here wants to discuss the design of a gate driver, I did
> it myself.

What's there to discuss? I use an ARM micro to monitor the (4S to 6S) backup battery voltages and shunt cells to a heavy load via a MOSFET with a PC123. People probably think it's overkill anyway.

My electronics run from batteries, with the main charging it occasionally.

On Sunday, June 6, 2021 at 7:56:37 AM UTC+10, jla...@highlandsniptechnology..com wrote:
> On Sat, 5 Jun 2021 14:09:29 -0700 (PDT), Fred Bloggs
> <bloggs.fred...@gmail.com> wrote:
>
> >On Saturday, June 5, 2021 at 4:23:26 PM UTC-4, jla...@highlandsniptechnology.com wrote:
> >> One of our customers returned a bunch of fried VME waveform generators
> >>
> >> http://www.highlandtechnology.com/DSS/V375DS.shtml
> >>
> >> They were installed in a VME crate that has a kinda clumsy push-push
> >> power switch. If you fumble with it just right, turn if off for about
> >> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
> >>
> >> Our modules don't like that. Some of the older FPGAs are powered
> >> directly from +5.
> >>
> >> So I've volunteered to make a clamp module. I'm thinking about three
> >> or four 1000 watt, 1000 amp mosfets and some sort of gate driver.
> >
> >Don't do that. Put a delay-on-break relay in line with the mains. It won't let power be re-applied for the timeout etc...
> >
> >
> It would be a major project to remove all the crates from a bunch of
> sites and add all that stuff. A plugin clamp would be an easy field
> addition.
>
> Looks like 10 or so surface-mount dpak fets would be nice. We have
> FDD86367 in stock. Each will conduct about 100 amps with 5.5v on the
> gate.
>
> Nobody in SED seems to want to actually D.

Not for nothing. if you had wanted to subcontract the job, you'd have had to specify it in more detail.

Specifying the FDD86387 at the part you want to drive was a start, but saying that you think you need ten of them doesn't characterise the current you think you need to clamp in much detail. It certainly doesn't specify the length of time you'll need to keep it clamped.

--
Bill Sloman, Sydney

On Saturday, June 5, 2021 at 2:56:37 PM UTC-7, jla...@highlandsniptechnology.com wrote:
> On Sat, 5 Jun 2021 14:09:29 -0700 (PDT), Fred Bloggs
> <bloggs.fred...@gmail.com> wrote:
>
> >On Saturday, June 5, 2021 at 4:23:26 PM UTC-4, jla...@highlandsniptechnology.com wrote:
> >> One of our customers returned a bunch of fried VME waveform generators
> >>
> >> http://www.highlandtechnology.com/DSS/V375DS.shtml
> >>
> >> They were installed in a VME crate that has a kinda clumsy push-push
> >> power switch. If you fumble with it just right, turn if off for about
> >> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
> >>
> >> Our modules don't like that. Some of the older FPGAs are powered
> >> directly from +5.
> >>
> >> So I've volunteered to make a clamp module. I'm thinking about three
> >> or four 1000 watt, 1000 amp mosfets and some sort of gate driver.
> >
> >Don't do that. Put a delay-on-break relay in line with the mains. It won't let power be re-applied for the timeout etc...
> >
> >
> It would be a major project to remove all the crates from a bunch of
> sites and add all that stuff. A plugin clamp would be an easy field
> addition.
>
> Looks like 10 or so surface-mount dpak fets would be nice. We have
> FDD86367 in stock. Each will conduct about 100 amps with 5.5v on the
> gate.

I can't find any info on this FET. Just because you have it doesn't mean it's the right chip for the job. You are essentially building a 5V shunt regulator, using 5.5V gate drive might not make much sense.

I would pick a N-FET with 2.5V gate drive. Since most micros are 3.3V output.

And you are not limited to just using 10 of them.

On 6/5/21 10:20 PM, Ed Lee wrote:
> On Saturday, June 5, 2021 at 2:56:37 PM UTC-7, jla...@highlandsniptechnology.com wrote:
>> On Sat, 5 Jun 2021 14:09:29 -0700 (PDT), Fred Bloggs
>> <bloggs.fred...@gmail.com> wrote:
>>
>>> On Saturday, June 5, 2021 at 4:23:26 PM UTC-4, jla...@highlandsniptechnology.com wrote:
>>>> One of our customers returned a bunch of fried VME waveform generators
>>>>
>>>> http://www.highlandtechnology.com/DSS/V375DS.shtml
>>>>
>>>> They were installed in a VME crate that has a kinda clumsy push-push
>>>> power switch. If you fumble with it just right, turn if off for about
>>>> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
>>>>
>>>> Our modules don't like that. Some of the older FPGAs are powered
>>>> directly from +5.
>>>>
>>>> So I've volunteered to make a clamp module. I'm thinking about three
>>>> or four 1000 watt, 1000 amp mosfets and some sort of gate driver.
>>>
>>> Don't do that. Put a delay-on-break relay in line with the mains. It won't let power be re-applied for the timeout etc...
>>>
>>>
>> It would be a major project to remove all the crates from a bunch of
>> sites and add all that stuff. A plugin clamp would be an easy field
>> addition.
>>
>> Looks like 10 or so surface-mount dpak fets would be nice. We have
>> FDD86367 in stock. Each will conduct about 100 amps with 5.5v on the
>> gate.
>
> I can't find any info on this FET.

https://www.onsemi.com/pdf/datasheet/fdd86367-d.pdf

> Just because you have it doesn't mean it's the right chip for the job. You are essentially building a 5V shunt
>regulator, using 5.5V gate drive might not make much sense.
>
> I would pick a N-FET with 2.5V gate drive. Since most micros are 3.3V output.
>
> And you are not limited to just using 10 of them.
>

On Saturday, June 5, 2021 at 10:45:26 PM UTC-7, RosemontCrest wrote:
> On 6/5/21 10:20 PM, Ed Lee wrote:
> > On Saturday, June 5, 2021 at 2:56:37 PM UTC-7, jla...@highlandsniptechnology.com wrote:
> >> On Sat, 5 Jun 2021 14:09:29 -0700 (PDT), Fred Bloggs
> >> <bloggs.fred...@gmail.com> wrote:
> >>
> >>> On Saturday, June 5, 2021 at 4:23:26 PM UTC-4, jla...@highlandsniptechnology.com wrote:
> >>>> One of our customers returned a bunch of fried VME waveform generators
> >>>>
> >>>> http://www.highlandtechnology.com/DSS/V375DS.shtml
> >>>>
> >>>> They were installed in a VME crate that has a kinda clumsy push-push
> >>>> power switch. If you fumble with it just right, turn if off for about
> >>>> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
> >>>>
> >>>> Our modules don't like that. Some of the older FPGAs are powered
> >>>> directly from +5.
> >>>>
> >>>> So I've volunteered to make a clamp module. I'm thinking about three
> >>>> or four 1000 watt, 1000 amp mosfets and some sort of gate driver.
> >>>
> >>> Don't do that. Put a delay-on-break relay in line with the mains. It won't let power be re-applied for the timeout etc...
> >>>
> >>>
> >> It would be a major project to remove all the crates from a bunch of
> >> sites and add all that stuff. A plugin clamp would be an easy field
> >> addition.
> >>
> >> Looks like 10 or so surface-mount dpak fets would be nice. We have
> >> FDD86367 in stock. Each will conduct about 100 amps with 5.5v on the
> >> gate.
> >
> > I can't find any info on this FET.
> https://www.onsemi.com/pdf/datasheet/fdd86367-d.pdf

OK, that's fine. But it says 2v to 4v gate voltage, not 5.5v

> > Just because you have it doesn't mean it's the right chip for the job. You are essentially building a 5V shunt
> >regulator, using 5.5V gate drive might not make much sense.
> >
> > I would pick a N-FET with 2.5V gate drive. Since most micros are 3.3V output.
> >
> > And you are not limited to just using 10 of them.
> >

On 6/5/21 10:54 PM, Ed Lee wrote:
> On Saturday, June 5, 2021 at 10:45:26 PM UTC-7, RosemontCrest wrote:
>> On 6/5/21 10:20 PM, Ed Lee wrote:
>>> On Saturday, June 5, 2021 at 2:56:37 PM UTC-7, jla...@highlandsniptechnology.com wrote:
>>>> On Sat, 5 Jun 2021 14:09:29 -0700 (PDT), Fred Bloggs
>>>> <bloggs.fred...@gmail.com> wrote:
>>>>
>>>>> On Saturday, June 5, 2021 at 4:23:26 PM UTC-4, jla...@highlandsniptechnology.com wrote:
>>>>>> One of our customers returned a bunch of fried VME waveform generators
>>>>>>
>>>>>> http://www.highlandtechnology.com/DSS/V375DS.shtml
>>>>>>
>>>>>> They were installed in a VME crate that has a kinda clumsy push-push
>>>>>> power switch. If you fumble with it just right, turn if off for about
>>>>>> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
>>>>>>
>>>>>> Our modules don't like that. Some of the older FPGAs are powered
>>>>>> directly from +5.
>>>>>>
>>>>>> So I've volunteered to make a clamp module. I'm thinking about three
>>>>>> or four 1000 watt, 1000 amp mosfets and some sort of gate driver.
>>>>>
>>>>> Don't do that. Put a delay-on-break relay in line with the mains. It won't let power be re-applied for the timeout etc...
>>>>>
>>>>>
>>>> It would be a major project to remove all the crates from a bunch of
>>>> sites and add all that stuff. A plugin clamp would be an easy field
>>>> addition.
>>>>
>>>> Looks like 10 or so surface-mount dpak fets would be nice. We have
>>>> FDD86367 in stock. Each will conduct about 100 amps with 5.5v on the
>>>> gate.
>>>
>>> I can't find any info on this FET.
>> https://www.onsemi.com/pdf/datasheet/fdd86367-d.pdf
>
> OK, that's fine. But it says 2v to 4v gate voltage, not 5.5v

Yes, it does. Take that up with Larkin. ;-)

>
>>> Just because you have it doesn't mean it's the right chip for the job. You are essentially building a 5V shunt
>>> regulator, using 5.5V gate drive might not make much sense.
>>>
>>> I would pick a N-FET with 2.5V gate drive. Since most micros are 3.3V output.
>>>
>>> And you are not limited to just using 10 of them.
>>>

On Saturday, June 5, 2021 at 10:54:04 PM UTC-7, Ed Lee wrote:
> On Saturday, June 5, 2021 at 10:45:26 PM UTC-7, RosemontCrest wrote:
> > On 6/5/21 10:20 PM, Ed Lee wrote:
> > > On Saturday, June 5, 2021 at 2:56:37 PM UTC-7, jla...@highlandsniptechnology.com wrote:
> > >> On Sat, 5 Jun 2021 14:09:29 -0700 (PDT), Fred Bloggs
> > >> <bloggs.fred...@gmail.com> wrote:
> > >>
> > >>> On Saturday, June 5, 2021 at 4:23:26 PM UTC-4, jla...@highlandsniptechnology.com wrote:
> > >>>> One of our customers returned a bunch of fried VME waveform generators
> > >>>>
> > >>>> http://www.highlandtechnology.com/DSS/V375DS.shtml
> > >>>>
> > >>>> They were installed in a VME crate that has a kinda clumsy push-push
> > >>>> power switch. If you fumble with it just right, turn if off for about
> > >>>> 3/4 of a second and turn it back on, the +5 bus spikes to about +9.
> > >>>>
> > >>>> Our modules don't like that. Some of the older FPGAs are powered
> > >>>> directly from +5.
> > >>>>
> > >>>> So I've volunteered to make a clamp module. I'm thinking about three
> > >>>> or four 1000 watt, 1000 amp mosfets and some sort of gate driver.
> > >>>
> > >>> Don't do that. Put a delay-on-break relay in line with the mains. It won't let power be re-applied for the timeout etc...
> > >>>
> > >>>
> > >> It would be a major project to remove all the crates from a bunch of
> > >> sites and add all that stuff. A plugin clamp would be an easy field
> > >> addition.
> > >>
> > >> Looks like 10 or so surface-mount dpak fets would be nice. We have
> > >> FDD86367 in stock. Each will conduct about 100 amps with 5.5v on the
> > >> gate.
> > >
> > > I can't find any info on this FET.
> > https://www.onsemi.com/pdf/datasheet/fdd86367-d.pdf
> OK, that's fine. But it says 2v to 4v gate voltage, not 5.5v

Yes, it does require close to 5.5v for meaningful current. I would pick another smaller one. Just use more of them.

> > > Just because you have it doesn't mean it's the right chip for the job. You are essentially building a 5V shunt
> > >regulator, using 5.5V gate drive might not make much sense.
> > >
> > > I would pick a N-FET with 2.5V gate drive. Since most micros are 3.3V output.
> > >
> > > And you are not limited to just using 10 of them.
> > >