I'm attempting to control an automotive solenoid with PWM at 1250hz. At peak, the solenoid draws 3.75 Amps at 14.4 Volts. The specific problem is that any MOSFET that I've tried gets too hot and destroys itself as I increase the PWM frequency. The fastest that I can successfully control the solenoid is 40hz with the BUK9275-100A. I designed a test PCB to isolate the solenoid, CMS04 freewheel diode, MOSFET and MCP1402 MOSFET driver.
Here are the MOSFETs I've tried:
- What MOSFET characteristics should I be looking at besides RDS(on) to successfully control this solenoid at 1250hz?
- Will I need to move away from the DPAK form factor to control the heat? I have up to 11 sqin of PCB surface to dissipate the heat.
- Is there anything potentially incorrect with my PCB layout for the driver? I plan to use the same driver layout for the MCP1402 in the production board.
I've added the schematic: http://www.firepunk.com/albums/About-Me/mosfetbreakout.png