Looking for a high speed low current pnp bjt to invert the output of an optocoupler

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kathmandu

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Looking for a high speed low current pnp bjt

hello,
please help me to find out a suitable high speed low current bjt (pnp, thru hole package). I want to invert the output of an optocoupler (6n137) and I want to use a lower collector current (1mA) but still having smaller switching times (bellow 50ns).
The usual pnp bjt (2n3906) only have small switching times for bigger collector currents (10-100mA range).
god bless u
 

Re: Looking for a high speed low current pnp bjt

Hi,

Not BJT, but PMOS ZVP2106A says 49 nanoseconds rise to fall, VGSth is -1.5V min. to -3.5V max., and as you know is not current dependent, unless you need current-controlled device for some reason. 2N2907 datasheet does have turn on at 100uA but is far, far too slow, apparently.

...datasheet says VGSth conditions: ID=-1mA, VDS= VGS
 
Re: Looking for a high speed low current pnp bjt

Thank you very much for your suggestions! I've just found a suitable part (https://www.applelogic.org/files/PN4258.pdf) but it seems to be obsolete and didn't found it on local stores neither (not even a replacement though).
I might try to look after a pmos as you have already suggested. The optocoupler has a supply voltage of 5v thus a Vgsth range of 1.5v to 3.5v looks ok. I already made the pcb hence I'm still looking for a bjt first.
 

Re: Looking for a high speed low current pnp bjt

You don't need to add a device to invert the output when you can invert the input by choosing either high or low side driving of LED ( anode-hi or Cathode-low)
 

Re: Looking for a high speed low current pnp bjt

(the original schematic has a speed-up capacitor and a backer clamp circuit (three schottky diodes) to improve the bjt switching characteristics thus it might be difficult to accommodate a pmos on the actual pcb)

- - - Updated - - -

SunnySkyguy said:
You don't need to add a device to invert the output when you can invert the input by choosing either high or low side driving of LED ( anode-hi or Cathode-low)
Click to expand...

It happened to accidentally disconnect the optocoupler wires and its output defaults to high thus I've got a mosfet shoot through (i'm driving a full bridge).
 

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