Forums

zener!

Started by John Larkin October 15, 2021
John Larkin wrote:
> On Fri, 15 Oct 2021 11:21:24 -0700 (PDT), Rich S > <richsulinengineer@gmail.com> wrote: > >> On Friday, October 15, 2021 at 6:01:14 PM UTC, John Larkin wrote: >>> https://www.digikey.com/en/products/detail/microchip-technology/JANS1N4102DUR-1-TR/13995295 >>> >>> Somebody must buy them. >>> >>> -- >>> >>> If a man will begin with certainties, he shall end with doubts, >>> but if he will be content to begin with doubts he shall end in certainties. >>> Francis Bacon >> >> Avalanche 8.7 volts, seems odd, probably associated with a one design or >> application. (input clamp?). >> Must be some extant military gear with support contract, keeping the >> (sub)contractor in business. >> $140 for a mil-spec part,.. I dunno, haven't kept up on these, but honestly isn't >> a surprise to me... >> >> =RS > > I need an 8.7 v 2% zener as a clamp, to protect a $300 distributed amp > chip rated for 9 volts abs max. Parts are hard to get lately. > > I'll go for 5% and pray. >
Would about 8.22V 1% do? Low power part as spec is 100uA nominal 500uA max (to 200C). Fudge by adding a diode in series, which can be thermally coupled, time constant maybe 10mSec worst case. Thanks, R.Baer -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus
On Sat, 16 Oct 2021 00:29:50 -0700, Robert Baer
<robertbaer@localnet.com> wrote:

>John Larkin wrote: >> On Fri, 15 Oct 2021 11:21:24 -0700 (PDT), Rich S >> <richsulinengineer@gmail.com> wrote: >> >>> On Friday, October 15, 2021 at 6:01:14 PM UTC, John Larkin wrote: >>>> https://www.digikey.com/en/products/detail/microchip-technology/JANS1N4102DUR-1-TR/13995295 >>>> >>>> Somebody must buy them. >>>> >>>> -- >>>> >>>> If a man will begin with certainties, he shall end with doubts, >>>> but if he will be content to begin with doubts he shall end in certainties. >>>> Francis Bacon >>> >>> Avalanche 8.7 volts, seems odd, probably associated with a one design or >>> application. (input clamp?). >>> Must be some extant military gear with support contract, keeping the >>> (sub)contractor in business. >>> $140 for a mil-spec part,.. I dunno, haven't kept up on these, but honestly isn't >>> a surprise to me... >>> >>> =RS >> >> I need an 8.7 v 2% zener as a clamp, to protect a $300 distributed amp >> chip rated for 9 volts abs max. Parts are hard to get lately. >> >> I'll go for 5% and pray. >> > Would about 8.22V 1% do? Low power part as spec is 100uA nominal >500uA max (to 200C). > Fudge by adding a diode in series, which can be thermally coupled, >time constant maybe 10mSec worst case. > > Thanks, R.Baer
The HMC659 output is rated 9 volts abs max. ADI says to take this very seriously, but they would. So I have a 1 pF schottky clamp diode (even that 1 pF is annoying) and then the biased-up bypassed 8.7v zener. It might have to dump 50 mA. I'd test the amp chip for actual breakdown, but we only have one in stock now and they cost $330 each. This is nominally an RF part, so it's likely it will really swing to at least 2x Vcc. That's something the RF boys tend to do, specify max supply voltage and not max device voltage. I'll eventually try it and maybe delete the clamp. I want all the swing I can get, but we only need to bias it high and pulse it in the down direction. -- Father Brown's figure remained quite dark and still; but in that instant he had lost his head. His head was always most valuable when he had lost it.
On Fri, 15 Oct 2021 23:57:46 -0700, Robert Baer
<robertbaer@localnet.com> wrote:

>John Larkin wrote: >> https://www.digikey.com/en/products/detail/microchip-technology/JANS1N4102DUR-1-TR/13995295 >> >> Somebody must buy them. >> > Cheap - - $3.54/week. > Could be low noise, as 8.7 V is in the low noise "valley"; especially >for certain manufacturers.
JAN is a military screened/qualified part. No wonder a fighter costs hundreds of millions each. -- Father Brown's figure remained quite dark and still; but in that instant he had lost his head. His head was always most valuable when he had lost it.
On Fri, 15 Oct 2021 11:01:04 -0700, John Larkin
<jlarkin@highland_atwork_technology.com> wrote:

>https://www.digikey.com/en/products/detail/microchip-technology/JANS1N4102DUR-1-TR/13995295 > >Somebody must buy them.
Microchip must have bought a business with a warehouse bin full of them - and digikey just auto-transfered their stock list. Aren't robots fun ? Welcome. Let me take your hat. RL
John Larkin wrote:
> On Fri, 15 Oct 2021 11:21:24 -0700 (PDT), Rich S > <richsulinengineer@gmail.com> wrote: > >> On Friday, October 15, 2021 at 6:01:14 PM UTC, John Larkin wrote: >>> https://www.digikey.com/en/products/detail/microchip-technology/JANS1N4102DUR-1-TR/13995295 >>> >>> Somebody must buy them. >>> >>> -- >>> >>> If a man will begin with certainties, he shall end with doubts, >>> but if he will be content to begin with doubts he shall end in certainties. >>> Francis Bacon >> >> Avalanche 8.7 volts, seems odd, probably associated with a one design or >> application. (input clamp?). >> Must be some extant military gear with support contract, keeping the >> (sub)contractor in business. >> $140 for a mil-spec part,.. I dunno, haven't kept up on these, but honestly isn't >> a surprise to me... >> >> =RS > > I need an 8.7 v 2% zener as a clamp, to protect a $300 distributed amp > chip rated for 9 volts abs max. Parts are hard to get lately. > > I'll go for 5% and pray. >
Did a little re-engineering, and see that the apparent power and size requirements of your zener look do-able while retaining the majority of the Codatron(R) specifications (on and off datasheet). Biggie: noise. Guarantee no avalanche type noise or oscillation from zero current to 500uA thru the Codatron(R) module. That current gets "amplified" by your choice of the current pass transistor which adds its Vbe to the total zener voltage. The module is connected from the base of your NPN current pass transistor to its collector; zener use from emitter to collector. Size of the Codatron(R) module? Perhaps SOT363. Size of your NPN current pass transistor? Up to you. Thanks, R. Baer -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus