High Speed MOSFET Driving with GPIO

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by neilt6 on Thu Jun 20 12:36:33 MST 2013

Hey guys. I'm trying to build a high-speed push-pull driver using a P-channel and N-channel MOSFET connected to a PWM pin on an LPC11U35, but I'm having a little trouble with choosing a gate resistor. My understading is that the gate resistor limits the instantaneous current caused by the gate capacitance. According to the LPC11U35 datasheet, the GPIO pins are only rated for about 4mA (Actually it says -4mA and I have no idea why, if anybody could shed light on this as well that'd be great), so I've been using 1.5k gate resistors up until now. However, I need this push-pull driver to swtich between 500kHz to 1MHz. This is obviously not going to happen with a 1.5k resistor, the output just sits high all the time. What do I need to do to make this work?