cross irf9640

[salim]

hi can i se irf640 instead irf9640 thanks

[porkluvr]

Sure. Just remember to reverse the power supply.

edit:
(trying to remember to be NICE...)

The answer is no.

IRF640 and IRF9640 are different polarity devices. They are -essentially- electrical mirror images of each other.

[salim]

hi
right irf640 200v 9640 -200v can you help me to find cross ref ? it is irf9540 a good substitute ? thanks br!

[porkluvr]

At least, now you are trying to compare two P-channel devices. You're getting "warmer".

BUT IRF9540 has breakdown voltage of only -100V and there is higher output capacitance. Not good.

Have you compared datasheets? If not, you should.

IRF9640 is an excellent "industry standard" device (my own opinion). It is manufactured by several different manufacturers, which suggests that it should be obtainable with reasonable effort. If you can't find it, you should KEEP LOOKING because any good substitutes are probably going to be as difficult or even more difficult to obtain and would very likely be more expensive.

[myonyuntwin]

can i replace irf9540 instead of irf9640?

[porkluvr]

IRF9540 has higher channel resistance (usually bad for power delivery) but lower inter-electrode capacitances (usually good for being able to sample sooner than would otherwise be normal).

You could try shorter tx pulses and see if you can get short flyback recovery times for detecting small targets. For longer tx pulses or more frequent short pulses (and higher power) you would better use a heatsink to help prevent overheating due to the higher channel resistance's I^2R losses.