Zener diodes in TO220 or similar?

[Joerg]

Joerg a écrit :

Borderline but... using a low voltage avalanche rated mosfet?

That's what Lasse also mentioned but I'd rather not ...

 

[Joerg]

That's TO262, SC83, SOT404 - D2pak for a mosfet.


Assuming you have somewhere for the heat to go.....

There is a metal structure.

As for real estate, have you considered wave-side smd component use?

Wave-side? I'd have to pipe the heat into some metal, some beefy metal.

 

[Joerg]

Go vertical, make the vertical board part of the main board panel.
Assemble the board as usual and v-score when you assemble it.

No vertical space at all, beyond the typical height of the parts :-(

 

[Joerg]

DO4 ? (ok, that one is not modern)

Well, so far I only found DO-5 for power zeners. Which is very wide
because they designed those for wrench-fastening.

 

[Jim Thompson]

More descriptively called 'roach wires' where I come from. IBM used to
call them 'yellow wires' back when you could use wire to run signals in
computers.

Cheers

Phil Hobbs

That would be back when computers were wired using punch-down blocks
and wire-wrap ?

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine Sometimes I even put it in the food

 

[Jim Thompson]

Phenolic terminal strips and 12AT7s.

Cheers

Phil Hobbs

And a big Weller "gun"... such nice smells ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine Sometimes I even put it in the food

 

[Joerg]

That would be back when computers were wired using punch-down blocks
and wire-wrap ?

It would be nice if they made similar ones for 24V truck systems. But
probably not much of a market because in many regions such as the US
trucks also run on 12V. Even really big rigs.

 

[Rich Grise]

Sure; just put a power NPN with low-wattage zener from collector
to base (base/emitter pulldown resistor optional). The good
news: Miller effect is on your side, for once!

And, with a little care, a zener in one of those little rectangular
packages could be soldered right across the leads!

Cheers!
Rich

 

[Joerg]

Have you looked at TVS diodes?

Yes, but they also don't come in TO-220 style packages so I can get the
accumulating energy off my back.

 

[Joerg]

And, with a little care, a zener in one of those little rectangular
packages could be soldered right across the leads!

It could but in this app that would likely be shot down as a
non-approvable kludge ;-)

 

[E]

Well, so far I only found DO-5 for power zeners. Which is very wide
because they designed those for wrench-fastening.

NTE makes DO4 NTE5174A thru NTE5232A. Expensive
http://www1.elfa.se/elfa~fi_fi/go.jsp?s=fi-fi&a=48CB877281B7453BE10000000A0A036A

 

[Jamie]

It's not to generate a controlled voltage but to dump unwanted spike
energy. Without creating smoke

But it looks like it will have to be a FET. Machining a DO-5 package to
a smaller size isn't exactly my favorite method.

Have you looked at TVS diodes?

 

[Joerg]

NTE makes DO4 NTE5174A thru NTE5232A. Expensive
http://www1.elfa.se/elfa~fi_fi/go.jsp?s=fi-fi&a=48CB877281B7453BE10000000A0A036A

NTE is expensive and often single source. Plus the thing is still over
30mm long:

https://www1.elfa.se/data1/wwwroot/webroot/Z_DATA/07007602.pdf

So same as with the DO-5, we'd have to machine that down.

 

[Joerg]

So mount it underneath the TO-220 lead bend.

And put an innocent looking dab of lacquer on it

 

[Joerg]

I was actually serious...something like a BZT52H-C68 68V Zener should
fit under there, nicely surface mounted, waiting for the TO-220 to be
hand-soldered into its through-hole mounting. Just using through holes
instead of SMT pads should save enough real estate for that.

Well, it's going to have to live in a remote location, off the board,
bolted to the chassis in a super-tight spot (to be able to heatsink),
leads clipped to the minimum and so on.

Took a look at your house on sat view. Looks like you've got a black
sedan and a white SUV

 

[Spehro Pefhany]

It could but in this app that would likely be shot down as a
non-approvable kludge ;-)

Actually, machining a semiconductor package down as you suggest is a
FAR more risky move reliability-wise.

 

[Joerg]

Actually, machining a semiconductor package down as you suggest is a
FAR more risky move reliability-wise.

That's why I don't even want to suggest it. With a zener it might be ok
but I'd rather not.

 

[legg]

Wave-side? I'd have to pipe the heat into some metal, some beefy metal.

I'm talking about using both sides of your board real estate for the
small stuff. If you're soldering TO262 or TO220AC bodies, presumably
in a wave soldering their through-hole leads (TO252 DPAK has smd leads
for reflow), the wave-side real estate could harbour resistors, zener,
caps and other 'smd' parts that are processed in the same wave
operation.

RL

 

[Joerg]

I'm talking about using both sides of your board real estate for the
small stuff. If you're soldering TO262 or TO220AC bodies, presumably
in a wave soldering their through-hole leads (TO252 DPAK has smd leads
for reflow), the wave-side real estate could harbour resistors, zener,
caps and other 'smd' parts that are processed in the same wave
operation.

Those kinds of designs usually have only very tiny stuff on the circuit
board. TSSOP, MSOP, 0402 or smaller, SC-75, but tons of it. All the
heavy parts such as TO-220 are off the board because they must be bolted
to a chassis.

 

[krw]

That would be back when computers were wired using punch-down blocks
and wire-wrap ?

Actually, a lot longer than that. They were still called that long
after they changed color and became twisted pair. ;-)