Pulsed Power in Resistor

[Rewn]

resistor pulse power

This is the problem: I have a 100 ohm resistor and there is going to be a pulse current of approximately .5A decreasing linearly from .5A to 0A in 80ns. This resistor is going to be connected to the gate of a power mosfet which is why there is this brief current. My question is, if this is going to be pulsed at a frequency of 10kHz, what resistor power must I use? I'm trying to decide what surface mount chip size would be appropriate.
Many Thanks!!!

 

[FvM]

pulse power resistor

I have a 100 ohm resistor and there is going to be a pulse current of approximately .5A decreasing linearly from .5A to 0A in 80ns.

Somewhat unlikely, cause it would involve 50 Vpp drive voltage. +/-15 would be maximum for usual MOSFET.

Apart from this point, the maximum pulse load depends on the resistor design and is different between types. Thickfilm chips have a rather low pulse capability, it's much higher with cylindrical (MELF) types. Also special high pulse load types are available from some manufacturers.

Generally, leading manufacturers are specifying maximum pulse load for different pulse durations.

In your application, the gate resistor is rather high. I'm used to gate resistors below 10 ohm with fast power stages. Thus I think, a 1206 thickfilm chip will be still O.K.

 

[FvM]

pulsed resistor current

This is a somewhat unusual problem that you have come across.

I think, it's a very common problem of IGBT and MOSFET drivers, except for the unusual resistance level.

 

[jdtoronto]

power resistor pulse current handling

Yes, it is far more typical to see 10R or even 4R7 in the gate. Typically I use 1206 size resistors for that purpose, but 0805 can be OK if you get metal film ones.

JD

 

[eem2am]

resistors pulse power

only very low power resistor is needed for you......the lowest of the low basically.

any resistor thats low inductance will be ok for you

so as long as you stay away from wirewound, then you are ok.

carbon i believe is best for you...metal film has slightly higher inductance than carbon