Selecting a diode

[ptewright]

Hi,

I'm trying to figure out how to choose a diode for my circuit.

I would like to place a diode across a 12V, 5A motor. This motor is pwm controlled @20kHz using a MOSFET. I am currently using a 1n4007 1A diode, because that is what I have at home.....Is this ok?
Should I be using a Schottky diode instead? What voltage and current rating should the diode have?

thanks!

 

[ZIGGY_DAN]

Prefferably you will need a diode capable of taking 12V at 5A, schottky diodes generally have faster switching speeds and so will probalbly be better for your particular application.

unless you are using it to dampen electromotive feedback, in which case it should have a higher voltage rating.

is this any help?

 

[ptewright]

I remember reading somewhere that I should select the ratings of the diode at least 1.5x greater than that of my motor specs.....but I guess I don't have to.......Thanks!

 

[philba]

I would definitely go for at least a 50V schottky. If your motor is running full spped and your reverse it, you will see some pretty significant kickback. especially if it is loaded. Running anything right at the spec limit is a bad idea anyway.