High voltage pnp's (250 volts)

H

Hul Tytus

Guest
sci.electronics.design, comp.arch.embedded
high voltage pnp's (250v)

Anyone know of a good pnp transistor spec'd up to 250 volts, a probable
current limit of 1 amp and designed as a switching device. It's to serve as
the switcher in a variable frequency (pulse width held constant) power supply.
So far a 2n2907 has been tried, with a 100ma 50 volt limit, with
impressive results. Zetex (now Diodes Inc) fzt957 & fzt958 with a 1 amp 300
volt limit were tried but they were inefective. The 2n2907 showed 47%
efficiency with a 500ns pulse width; the fzt957 showed 38%. With 4 micro
second widths, 2n2907 showed 61% & fxt957 showed 32% ().
Apparantly, the higher collector/emitter voltage implies a greater
effective restance and higher saturation voltage, which might explain why n
channel fets with convoluted "high side" drive circuitry are used. I'm hoping
there are some pnp devices in the relatively low 1 amp and 2 amp range that
are more useful than the fzt957 units. Any suggestions?

Hul
 
On 2020-04-14 09:44, Hul Tytus wrote:
sci.electronics.design, comp.arch.embedded
high voltage pnp's (250v)

Anyone know of a good pnp transistor spec'd up to 250 volts, a probable
current limit of 1 amp and designed as a switching device. It's to serve as
the switcher in a variable frequency (pulse width held constant) power supply.
So far a 2n2907 has been tried, with a 100ma 50 volt limit, with
impressive results. Zetex (now Diodes Inc) fzt957 & fzt958 with a 1 amp 300
volt limit were tried but they were inefective. The 2n2907 showed 47%
efficiency with a 500ns pulse width; the fzt957 showed 38%. With 4 micro
second widths, 2n2907 showed 61% & fxt957 showed 32% ().
Apparantly, the higher collector/emitter voltage implies a greater
effective restance and higher saturation voltage, which might explain why n
channel fets with convoluted "high side" drive circuitry are used. I'm hoping
there are some pnp devices in the relatively low 1 amp and 2 amp range that
are more useful than the fzt957 units. Any suggestions?

Hul

Need more info--pulse width and schematic in particular.
Click to expand...

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
Hul Tytus wrote...
sci.electronics.design, comp.arch.embedded
high voltage pnp's (250v)

Anyone know of a good pnp transistor spec'd up to 250 volts
Click to expand...

Suggest using a MOSFET, good choices all the way to 600V.


--
Thanks,
- Win
 
On 4/14/2020 9:44 AM, Hul Tytus wrote:
sci.electronics.design, comp.arch.embedded
high voltage pnp's (250v)

Anyone know of a good pnp transistor spec'd up to 250 volts, a probable
current limit of 1 amp and designed as a switching device. It's to serve as
the switcher in a variable frequency (pulse width held constant) power supply.
So far a 2n2907 has been tried, with a 100ma 50 volt limit, with
impressive results. Zetex (now Diodes Inc) fzt957 & fzt958 with a 1 amp 300
volt limit were tried but they were inefective. The 2n2907 showed 47%
efficiency with a 500ns pulse width; the fzt957 showed 38%. With 4 micro
second widths, 2n2907 showed 61% & fxt957 showed 32% ().
Apparantly, the higher collector/emitter voltage implies a greater
effective restance and higher saturation voltage, which might explain why n
channel fets with convoluted "high side" drive circuitry are used. I'm hoping
there are some pnp devices in the relatively low 1 amp and 2 amp range that
are more useful than the fzt957 units. Any suggestions?

Hul
Click to expand...

Mouser returns about one result meeting the spec:

<https://www.mouser.com/ProductDetail/Diodes-Incorporated/FZT957TA?qs=%2Fha2pyFaduhqELsujNN8ohHMXBps2fbPOzeaCD3dILxCoa4U1fpnvQ%3D%3D>

Looks like a very nice part and has a high current gain (unusual for HV
PNPs I think) but at $1 in singles, not cheap.
 
On 4/14/2020 3:35 PM, bitrex wrote:
On 4/14/2020 9:44 AM, Hul Tytus wrote:
sci.electronics.design, comp.arch.embedded
high voltage pnp's (250v)

    Anyone know of a good pnp transistor spec'd up to 250 volts, a
probable
current limit of 1 amp and designed as a switching device. It's to
serve as
the switcher in a variable frequency (pulse width held constant) power
supply.
    So far a 2n2907 has been tried, with a 100ma 50 volt limit, with
impressive results. Zetex (now Diodes Inc) fzt957 & fzt958 with a 1
amp 300
volt limit were tried but they were inefective. The 2n2907 showed 47%
efficiency with a 500ns pulse width; the fzt957 showed 38%. With 4 micro
second widths, 2n2907 showed 61% & fxt957 showed 32% ().
    Apparantly, the higher collector/emitter voltage implies a greater
effective restance and higher saturation voltage, which might explain
why n
channel fets with convoluted "high side" drive circuitry are used. I'm
hoping
there are some pnp devices in the relatively low 1 amp and 2 amp range
that
are more useful than the fzt957 units. Any suggestions?

Hul


Mouser returns about one result meeting the spec:

https://www.mouser.com/ProductDetail/Diodes-Incorporated/FZT957TA?qs=%2Fha2pyFaduhqELsujNN8ohHMXBps2fbPOzeaCD3dILxCoa4U1fpnvQ%3D%3D


Looks like a very nice part and has a high current gain (unusual for HV
PNPs I think) but at $1 in singles, not cheap.
Click to expand...

oops, you already found that one, didn't read carefully :)
 
On 4/14/2020 10:58 AM, Winfield Hill wrote:
Hul Tytus wrote...

sci.electronics.design, comp.arch.embedded
high voltage pnp's (250v)

Anyone know of a good pnp transistor spec'd up to 250 volts

Suggest using a MOSFET, good choices all the way to 600V.
Click to expand...

What about the 2N5415 apparently you can still get 'em:

<https://www.mouser.com/ProductDetail/Central-Semiconductor/2N5415-PBFREE?qs=sGAEpiMZZMve4%2FbfQkoj%252BLZHvMXp4Si4f9fQJjExGMA%3D>
 
Phil - you might read the message again.

Hul

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2020-04-14 09:44, Hul Tytus wrote:
sci.electronics.design, comp.arch.embedded
high voltage pnp's (250v)

Anyone know of a good pnp transistor spec'd up to 250 volts, a probable
current limit of 1 amp and designed as a switching device. It's to serve as
the switcher in a variable frequency (pulse width held constant) power supply.
So far a 2n2907 has been tried, with a 100ma 50 volt limit, with
impressive results. Zetex (now Diodes Inc) fzt957 & fzt958 with a 1 amp 300
volt limit were tried but they were inefective. The 2n2907 showed 47%
efficiency with a 500ns pulse width; the fzt957 showed 38%. With 4 micro
second widths, 2n2907 showed 61% & fxt957 showed 32% ().
Apparantly, the higher collector/emitter voltage implies a greater
effective restance and higher saturation voltage, which might explain why n
channel fets with convoluted "high side" drive circuitry are used. I'm hoping
there are some pnp devices in the relatively low 1 amp and 2 amp range that
are more useful than the fzt957 units. Any suggestions?

Hul

Need more info--pulse width and schematic in particular.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
Click to expand...
 
On 4/14/2020 3:44 PM, bitrex wrote:
On 4/14/2020 10:58 AM, Winfield Hill wrote:
Hul Tytus wrote...

sci.electronics.design, comp.arch.embedded
high voltage pnp's (250v)

Anyone know of a good pnp transistor spec'd up to 250 volts

  Suggest using a MOSFET, good choices all the way to 600V.



What about the 2N5415 apparently you can still get 'em:

https://www.mouser.com/ProductDetail/Central-Semiconductor/2N5415-PBFREE?qs=sGAEpiMZZMve4%2FbfQkoj%252BLZHvMXp4Si4f9fQJjExGMA%3D
Click to expand...

Or to meet the 250 volts the 2N5416 but gosh it's 9 bucks.

<https://www.mouser.com/ProductDetail/Microchip-Microsemi/2N5416?qs=sGAEpiMZZMshyDBzk1%2FWi3gIxHGWJeuopI2V%2FQhoag%252BvDhmuQlpDyA%3D%3D>
 
If you look at a power stage with less than 0.5A or so, a BJT has lower conduction loss for the same price vs a FET

Problem is they are a lot more sensitive to overvoltage, secondary breakdown and are a pain to drive (or so one would think)

Even though beta is small and base currents seems excessive, they are only multiplied with base voltage, so ends up with low base drive, conduction loss wise
 
Hul Tytus wrote:

=====================

I'm hoping
there are some pnp devices in the relatively low 1 amp and 2 amp range that are more useful than the fzt957 units. Any suggestions?
Click to expand...

** The MJE15035 is gonna be hard to beat.

https://www.onsemi.com/pub/Collateral/MJE15034-D.PDF


BTW: your Q is all over the place, like mad woman's breakfast.



..... Phil
 
This is dirt cheap :

https://www.mouser.dk/datasheet/2/389/dm00040355-1797494.pdf

You need to drive the base either hard negative to shut it off fast or use a baker clamp type method

Cheers

Klaus
 
Klaus - what's the "baker clamp" method? I've been woking along the line you suggest: first driving the transistor from 3 pal'd AT13
outputs through 3300 pf parrallel with 3300pf in series w/580 ohms along with a diode & 10k resistor to maintain bias. On the scope that
appears pretty good with just a hint of curvature in fall time when measured at the AT13 output. With just one output, the curvature is
quite noticable.

Hul


klaus.kragelund@gmail.com wrote:
This is dirt cheap :

https://www.mouser.dk/datasheet/2/389/dm00040355-1797494.pdf

You need to drive the base either hard negative to shut it off fast or use a baker clamp type method

Cheers

Klaus
Click to expand...
 
I'll take a look. Thanks

Hul

bitrex <user@example.net> wrote:
On 4/14/2020 10:58 AM, Winfield Hill wrote:
Hul Tytus wrote...

sci.electronics.design, comp.arch.embedded
high voltage pnp's (250v)

Anyone know of a good pnp transistor spec'd up to 250 volts

Suggest using a MOSFET, good choices all the way to 600V.



What about the 2N5415 apparently you can still get 'em:

https://www.mouser.com/ProductDetail/Central-Semiconductor/2N5415-PBFREE?qs=sGAEpiMZZMve4%2FbfQkoj%252BLZHvMXp4Si4f9fQJjExGMA%3D
Click to expand...
 
By the way the baker clamp is difficult to tune robustly for low VCE

If you know your load you can do intelligent trimming, but that is even more flaky

Last I looked at it there is tons of papers and patents on these techniques
 
Hi

I do not know the AT13, do you have a link?

About baker clamp:

https://en.m.wikipedia.org/wiki/Baker_clamp

It’s used to make sure the npn is never hard on which would cause long storage time when turning off

Cheers

Klaus
 
On 2020-04-14 18:06, Klaus Kragelund wrote:
By the way the baker clamp is difficult to tune robustly for low VCE

If you know your load you can do intelligent trimming, but that is even more flaky

Last I looked at it there is tons of papers and patents on these techniques
Click to expand...

Any favourite references?

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On 2020-04-14 15:01, Hul Tytus wrote:
> Phil - you might read the message again.

I see a reference to a 500 ns pulse width--is that a design requirement?

Still no schematic. I'd be interested to see it, whether or not I could
contribute. Your call.

Cheers

Phil Hobbs
 
On Wednesday, April 15, 2020 at 2:00:03 AM UTC+2, Phil Hobbs wrote:
On 2020-04-14 18:06, Klaus Kragelund wrote:
By the way the baker clamp is difficult to tune robustly for low VCE

If you know your load you can do intelligent trimming, but that is even more flaky

Last I looked at it there is tons of papers and patents on these techniques


Any favourite references?
Click to expand...

There is a lot of IEEE papers, but you need access to get those, and the wording is hidden, so cannot just search for "baker" clamp

This app note is ok:

http://notes-application.abcelectronique.com/040/40-33424.pdf

Some of the better patents:

https://patentimages.storage.googleapis.com/9b/13/fa/0bbacd5941291d/US20030062931A1.pdf

https://patentimages.storage.googleapis.com/f4/fc/c9/539a73945189d6/US4013903.pdf
 
On 14/04/2020 2:44 pm, Hul Tytus wrote:
sci.electronics.design, comp.arch.embedded
high voltage pnp's (250v)

Anyone know of a good pnp transistor spec'd up to 250 volts, a probable
current limit of 1 amp and designed as a switching device. It's to serve as
the switcher in a variable frequency (pulse width held constant) power supply.
So far a 2n2907 has been tried, with a 100ma 50 volt limit, with
impressive results. Zetex (now Diodes Inc) fzt957 & fzt958 with a 1 amp 300
volt limit were tried but they were inefective. The 2n2907 showed 47%
efficiency with a 500ns pulse width; the fzt957 showed 38%. With 4 micro
second widths, 2n2907 showed 61% & fxt957 showed 32% ().
Apparantly, the higher collector/emitter voltage implies a greater
effective restance and higher saturation voltage, which might explain why n
channel fets with convoluted "high side" drive circuitry are used. I'm hoping
there are some pnp devices in the relatively low 1 amp and 2 amp range that
are more useful than the fzt957 units. Any suggestions?

Hul
Click to expand...

My go-to jelly bean HV PNP is the MPSA92 but that might struggle above
500mA. Can you spare some Vce and use one of those in a Sziklai with a
beefier NPN?

Have you checked if the MJE5731 fits? But a p-channel MOSFET may work
better. These may help: IRFR9214; FQT2P25; FQP9P25.

More details of your circuit should help us find an answer.

piglet
 
On Wednesday, April 15, 2020 at 12:22:32 PM UTC+2, piglet wrote:
On 14/04/2020 2:44 pm, Hul Tytus wrote:
sci.electronics.design, comp.arch.embedded
high voltage pnp's (250v)

Anyone know of a good pnp transistor spec'd up to 250 volts, a probable
current limit of 1 amp and designed as a switching device. It's to serve as
the switcher in a variable frequency (pulse width held constant) power supply.
So far a 2n2907 has been tried, with a 100ma 50 volt limit, with
impressive results. Zetex (now Diodes Inc) fzt957 & fzt958 with a 1 amp 300
volt limit were tried but they were inefective. The 2n2907 showed 47%
efficiency with a 500ns pulse width; the fzt957 showed 38%. With 4 micro
second widths, 2n2907 showed 61% & fxt957 showed 32% ().
Apparantly, the higher collector/emitter voltage implies a greater
effective restance and higher saturation voltage, which might explain why n
channel fets with convoluted "high side" drive circuitry are used. I'm hoping
there are some pnp devices in the relatively low 1 amp and 2 amp range that
are more useful than the fzt957 units. Any suggestions?

Hul


My go-to jelly bean HV PNP is the MPSA92 but that might struggle above
500mA. Can you spare some Vce and use one of those in a Sziklai with a
beefier NPN?

Have you checked if the MJE5731 fits? But a p-channel MOSFET may work
better. These may help: IRFR9214; FQT2P25; FQP9P25.

More details of your circuit should help us find an answer.
Click to expand...

APT27 is also extremely cheap, 0.5A:

https://www.diodes.com/assets/Datasheets/APT27.pdf

Beta is ok up to 200mA
 
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