low power, HV-in regulator with depletion mosfet

I don't see any problems with the simple little application suggestions in the Ixys note, I do see a lot of critique from people who either don't understand how depletion FETs work or the type of depletion FET to be used in the various applications.

It doesn't have any initial accuracy or load regulation worth wasting parts on. And doesn't look like it will withstand transients off the HV.

Ixys note, I do see a lot of critique from people who either don't understand how depletion FETs work or the type of depletion FET to be used in the various applications.

There are too many stupidities to go into just now. Maybe later

And doesn't look like it will withstand transients off the HV.

It's plenty accurate to power opamps. Load reg is good up to the current limit... it has tons of loop gain. Rout is about 3 ohms, plenty good enough to power 10 or 20 mA of opamps.

The HV is bypassed by 30,000 uF, so I don't expect much in the way of transients. But it is a 300 volt depletion fet, so it could ride through any transients up to there.

Crss of the fet is 5 pF and Ciss is 300. No drain spike is going to punch through the gate.

It'll work.

Ghastly bad poet, too. Really, really bad.

Ghastly bad horse's ass, you are. It'd be really pleasant around here if you'd knock off the continual obnoxii. ...Jim Thompson

So will this and it's at least as good as your depletion mode circuit: Please view in a fixed-width font such as Courier.

. . . . . 48V>---[1.8K]-----+-------> . | . | . ---/ . // \ 12V . --- . | . | . ---------------+--------- . . . . . .

Don't give up your retirement..

I only say that because I can't see you being employed, except maybe at a grocery store as a door receptionist.

Jamie

As I noted, it has to work from 18 volts in to 48.

That doesn't.

And it dissipates almost a watt at 48 volts.

When did you mention 18V? That's quite a swing on a 48V nominal supply. Is that steady state or some transient dip?

steady state or some transient dip?

Steady-state. I mentioned that a few days ago.

And since I'm driving opamps that deliver signals to a customer, and he could load some of them, I do want a regulator with a little current reserve. Which is why I set the current limit to about 40 mA.

There have been lots of John Larkins, some famous and some notorious.

--

John Larkin Highland Technology Inc

Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators

--- My guess is that, in your case, even though you've come in with a shout you'll go out with a whimper and leave nothing behind but cookie cutter "designs" which you gleaned from under the feet of the adequate.

I guess that's the role of a good engineer, as you've stated earlier, but one would think that, if you aspired to the higher calling to which you pretend, you'd wind up with something inventive to which your name was attached.

There's the Faraday disc, the Darlington connection, the Cuk converter, and the Larkin ???

-- JF

Company.

You're a walking advertisement for the 'Short Bus Driver's Union'.

Ah, a famous terrorist.

And a scoundrel.

And a flatfoot.

And a musician, of sorts.

Larkin butt buddy. ...Jim Thompson

-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85140 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at