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
High voltage pnp's (250 volts)
Started by ●April 14, 2020
Reply by ●April 14, 20202020-04-14
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
Reply by ●April 14, 20202020-04-14
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 voltsSuggest using a MOSFET, good choices all the way to 600V. -- Thanks, - Win
Reply by ●April 14, 20202020-04-14
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
Reply by ●April 14, 20202020-04-14
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.
Reply by ●April 14, 20202020-04-14
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.oops, you already found that one, didn't read carefully :)
Reply by ●April 14, 20202020-04-14
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>
Reply by ●April 14, 20202020-04-14
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> >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>
Reply by ●April 14, 20202020-04-14
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
Reply by ●April 14, 20202020-04-14
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?** 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
