KrisKasprzak
Well-known member
All,
I've been struggling for 3 years trying to figure out how to drive a mosfet at say 20,000 hz. My set up is a simple test board where my load is a power resistor drawing 3 amps at around 15 volts. The problem I'm running into at frequencies above 500 hz is that the mosfet gets extremely hot after 3-4 seconds (like 2nd degree burns on your finger hot). Running pwm at low hz (500) the mosfet runs fine and cool--only issue is the nasty buzz at that low frequency. I want to run higher frequency, but can't figure out how. i have a snubber diode across the resistor but, it makes no difference regarding temp.
Goals: vary current from 0-4 amps at 15 volts, using a teensy 3.2.
Here's what I've tried
Teensy with analogWrite on pin 6, with pwm frequency at 20,000 hz and these hardware configurations:
1. I've tried connecting teensy pwm pin directly to the mosfet gate, mosfet got very hot after 2-3 sec
2. I've tried using an optoisolator to get higher gate voltage, mosfet still runs hot
3. I've tried using a bjt transistor to get higher gate voltage, mosfet still runs hot
4. I've tried a special mosfet driver ir2125, i can't even get that thing working.
My knowledge of deciphering data sheets and electronics is quite limited, and im very frustrated with what should be a simple task. Maybe it's the mosfet i've selected, maybe mosfets can't be driven at high frequencies, i really have no clue. Mosfet i'm using is https://www.digikey.com/product-det...0P04P4L03AKSA1/IPP120P04P4L03AKSA1-ND/5960348 , but heck i'll try anything at this point
Can someone do me a huge favor and draw up a schematic with part numbers so i can run a mosfet at say 20,000 hz?
Thanks in advance.
Kris
I've been struggling for 3 years trying to figure out how to drive a mosfet at say 20,000 hz. My set up is a simple test board where my load is a power resistor drawing 3 amps at around 15 volts. The problem I'm running into at frequencies above 500 hz is that the mosfet gets extremely hot after 3-4 seconds (like 2nd degree burns on your finger hot). Running pwm at low hz (500) the mosfet runs fine and cool--only issue is the nasty buzz at that low frequency. I want to run higher frequency, but can't figure out how. i have a snubber diode across the resistor but, it makes no difference regarding temp.
Goals: vary current from 0-4 amps at 15 volts, using a teensy 3.2.
Here's what I've tried
Teensy with analogWrite on pin 6, with pwm frequency at 20,000 hz and these hardware configurations:
1. I've tried connecting teensy pwm pin directly to the mosfet gate, mosfet got very hot after 2-3 sec
2. I've tried using an optoisolator to get higher gate voltage, mosfet still runs hot
3. I've tried using a bjt transistor to get higher gate voltage, mosfet still runs hot
4. I've tried a special mosfet driver ir2125, i can't even get that thing working.
My knowledge of deciphering data sheets and electronics is quite limited, and im very frustrated with what should be a simple task. Maybe it's the mosfet i've selected, maybe mosfets can't be driven at high frequencies, i really have no clue. Mosfet i'm using is https://www.digikey.com/product-det...0P04P4L03AKSA1/IPP120P04P4L03AKSA1-ND/5960348 , but heck i'll try anything at this point
Can someone do me a huge favor and draw up a schematic with part numbers so i can run a mosfet at say 20,000 hz?
Thanks in advance.
Kris