I have a hardware problem. It's my 1st time I am using a medium voltage power mosfet. The mosfet is the IRFR9024:
I need to drive the Mosfet using a micro (Vcc = 5Vdc) in switching mode with 25us period(~40KHz) and 8 bit resolution duty cycle.
The mosfet's sourse voltage is 55Vdc and as the datasheet says the Vgs must be in the range of +/-20Vdc.
Looking at Fig.3 I see that for -Vgs < 4V the -Id = 0 (aprox.) and for -Vgs > 10V the -Id = high (Low Rds).
So if I understand it well I need a Gate Voltage:
For given Vs = 55V
- For Low Rds (Mosfet saturation): 35V < Vg < 45V
- For High Rds (Mosfet cut off): 51 < Vg < 55V
So the Gate (Vg) pulse must be like this:
55V (cut off) ------- ------- --- | | | | | | | | | | 35V (satur) ___| |______| |______|
1. Please confirm if I am saying it right.
2. What do you suggest me to do in order to drive the mosfet from the microcontroller pin?
For Vds = 55V(max) the Mosfet's Gate capacitance doesn't exceed the 1000pF and as I said before the Period is 25us and one step of duty cycle times ~10ns.