1. Home
  2. Electronics Design
  3. No more high voltage PNP transistors?

No more high voltage PNP transistors?

Folks,

When looking for small-signal high voltage PNP I was disappointed. Nothing available above 500V anymore and ideally I need north of 1kV at less than 2mA. I know the old CRT TV sets are gone for good but isn't there some specialty company that still makes such high voltage transistor?

In the normal range the FMMT560 at 500V and the STN9360 at 600 seem to be the end of the rope. Where the STN is officially listed for switching and I need linear but that may be ok.

For NPN and FETs it doesn't look a whole lot better and they'd not be well suited in this case.

There is always the option to cascade but that gets old when there are multiple strings needed.

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg
Loading thread data ...

1KV at 2 mA is 2 watts, not really small-signal any more.

Does it gotta be PNP bipolar? Does it gotta be cheap?

There are dpak n-channel mosfets up to 1500 volts. I cascode them with an optocoupler to avoid nasty gate voltage drivers.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

Depending on your application a depletion-mode MOSFET might do for the pull-up, as in...

...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)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.
Reply to
Jim Thompson

formatting link
have some internesting optocoupers in the HV range, photodiode output types/

The lowest voltage they have is 2500V. PN OC025 Very simple via 1.7 Vf led at 50mA. PD is only 125mW but for most apps of this nature, I think that would do just fine.

They go up to 25KV, and it looks like they are working on a 50Kv type.

jamie

Reply to
M Philbrook

It's only for bursts that it needs to do this much. SOT223 would be nice.

For at least one of them, yes. But I'll see if I go N-channel or do the cascade.

Not within reason. Meaning $1 would be ok, $2 painful, $5 not ok.

The drive in my case would be nasty. I could do an RF+rectifier drive but it ain't pretty.

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

Unfortunately they only go to 500V. The STN9360 at least goes to 600V but I'd have to find out if there are any pathologies when using it as a linear device. It's from ST and getting answers from their support has proven to be like kicking an oak tree unless it's a key account project and this project isn't.

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

We just bought 50 pieces of 2SK4177, 1500 volt n-channel, for $3.25 each. 1KV, in quantity, should be a lot cheaper.

Optocouple it! If you don't need speed, a PV coupler would be spiffy. It becomes a kilovolt linear SSR.

Two depletion fets and a regular optocoupler would work, too. Cheap.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

On a sunny day (Tue, 08 Dec 2015 13:33:04 -0800) it happened Joerg wrote in :

Use a NPN upside down?

Everything is relative ye noo

Reply to
Jan Panteltje

high voltage optocoupler?

--
  \_(?)_
Reply to
Jasen Betts

Upside down wouldn't work. You have to use it inside-out. ;)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

Do tubes come in P channel? Can you make holes in vacuum? Do you need to use antimatter? Interfacing could be a problem...

--


----Android NewsGroup Reader---- 
http://usenet.sinaapp.com/
Reply to
bitrex

Well, you could use an ion gun. Might be a bit hard on the anode, as well as being thousands of times slower.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

Very good, and even US-sourced.

I could do that. But then I'd be about at the complexity of a beanstalk which would also work here and be even cheaper.

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

A 6KD6 in P-channel, that would be the solution :-)

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

Sure, but only the isolation path is high voltage, not the output device. So then I'd also need depletion mode FETs which are a bit boutiquish and don't come >500V either.

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

This isn't bad:

formatting link

Reply to
John Larkin

That is nice. I'd probably add some angst diodes.

But I'll use the FMMT560 in a stack. At about 15c cents a pop it is hard to pass up.

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

On a sunny day (Wed, 9 Dec 2015 10:41:46 -0500) it happened Phil Hobbs wrote in :

Unless Joe post a circuit it is hard to tell, I think he often refers to inside out modified transistors by accident so to speak.

If it is a single stage output I really see no problem making it NPN. And dual NPN totempoles were in many audio amp output stages, even video out drivers.

Reply to
Jan Panteltje

That will need a couple of resistors to bias the halfway-up base. That's OK if you don't mind that current.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

The FMMT560 has a guaranteed hfe of 80 until way past 10mA so the resistor losses are reasonable. I needed a resistor there anyways and it had to be split up because of voltage rating limits so it doesn't even cost me extra. Nice thing is it also comes in a SOT223 flavor for when more muscle is required.

Of course, one must not forget the transistor capacitances in all that when things have to act fast. That's where the beanstalk has a real disadvantage. But the simulator says it's got plenty of margin.

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.