MP6532 driver immediately enters fault condition

I’m trying to drive a simple ebike hub BLDC motor (24V, 250W) with the MP6532. I built my own PCB using the EVM schematics with an onboard MCU (STM32F103). For the initial test, I’m reading a potentiometer and converting its value to a proportional duty cycle. The PWM frequency is 20KHz. DT is 200kohm and OCREF is 2V.

When the pot reaches a certain value (a duty cycle of about 5%), the motor seems to spin for a fraction of a second before a fault triggers and the nFAULT pin goes low. What may be causing this fault condition and how do I debug this?

UPDATE: I have the nFAULT pin with a 10K pull-up that goes to the MCU where it gets read as an interrupt. There is also a test pad on the nFAULT line. The pin seems to be very sensitive. Even when I try and measure the voltage on this pin, it goes low and triggers a fault condition. Also, right after a reset (when the PWM duty cycle is still 0), if I even slightly turn the motor wheel manually, a fault condition triggers.

Hello hrishikesh,

Thank you for contacting the MPS Forum. I have seen your question and will try to get an answer as soon as possible.

Thank you,

Vinh Tran
Field Applications
Monolithic Power Systems

Hello Vinh,

I figured this out. I had a small value MOSFET gate resistor. I calculated the right resistors for my MOSFETs to be about 150R and with that everything works now.