Other Parts Discussed in Thread: DRV8353
Hi,
Am driving a 350W BLDC motor with 37v, 20Khz PWM
Am seeing an undershoot of about -4v at the low side MOSFET gate when the high side MOSFET turns ON. With the no-load current of 200mA everything seems OK but when load increases with the current rising closer to 3A this undershoot starts
Waveform with Phase A LS gate [Cyan] and Phase A HS MOSFET gate [Yellow]
IDRIVE setting for all four gates are the lowest 0x00 [50mA]
Observation:
1. At no-load conditions the rise time of the HS gate is more than 150ns so undershoot is not seen
2. But, when the motor load increases the load current also increases up to 5A, at this time the HS gate rise time reduces to <70ns which causes the negative transient
3. This negative transient increases when the load increases
From the datasheet, I found an Absolute maximum rating for undershoot is -5v max, so as the undershoot is directly proportional to load I am sure this will violate the max transient of -5v soon
Please suggest me a solution to overcome this
FYI, am using a common current sense resistor for all 3 phases
thanks,
Amutha