Details. PIC16F685, 16Mhz with 5v+ rail. Using the PIC's ECCP which is designed for H-Bridge PWM.
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Bridge
P-Channels were IRLML6402 Logic level
N-Channels were IRLML2502 Logic level
16v to 18v on Bridge
PWM 18khz to drive the N-Channels.
Pullup resistors 10K on P-Channel
Pulldown resistors 10K on N-Channel
The bottom N-Channels have the PWM, the top P-Channels only switch on or off depending on direction.
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I created two PCB's, one with the H-Bridge and one with the MCU.
When testing the H-Bridge PCB without the MCU connected everything worked well. This was my tests for the bridge below
Forward,
Ground Left P-Channel Gate, applied 5V+ to N-Channel gate. Motor turned. Disconnect P-Channel gate and motor stopped. Reconnecedt P-Channel and discounted N-Channel gate and motor stopped.
Reverse
Same as Forward but with the Top Right P-Channel, and Bottom Left N-Channel. Tested with no problem.
Powersupply showed no accessive current draw.
Connected the PIC, turned it on, motor turned in forward direction. Them SMOKE started coming out of the FET, I think it was the bottom N-Channel.
Question?????????
Am I driving the FET's to fast with 18khz ?
Have I choosen the wrong resistor values ?
******************************
Bridge
P-Channels were IRLML6402 Logic level
N-Channels were IRLML2502 Logic level
16v to 18v on Bridge
PWM 18khz to drive the N-Channels.
Pullup resistors 10K on P-Channel
Pulldown resistors 10K on N-Channel
The bottom N-Channels have the PWM, the top P-Channels only switch on or off depending on direction.
******************************
I created two PCB's, one with the H-Bridge and one with the MCU.
When testing the H-Bridge PCB without the MCU connected everything worked well. This was my tests for the bridge below
Forward,
Ground Left P-Channel Gate, applied 5V+ to N-Channel gate. Motor turned. Disconnect P-Channel gate and motor stopped. Reconnecedt P-Channel and discounted N-Channel gate and motor stopped.
Reverse
Same as Forward but with the Top Right P-Channel, and Bottom Left N-Channel. Tested with no problem.
Powersupply showed no accessive current draw.
Connected the PIC, turned it on, motor turned in forward direction. Them SMOKE started coming out of the FET, I think it was the bottom N-Channel.
Question?????????
Am I driving the FET's to fast with 18khz ?
Have I choosen the wrong resistor values ?