Other Parts Discussed in Thread: LM5155
Customer 8316 product board, ear is attached to PCB board chip circuit, the current sound is more obvious, DRVOFF will have, The current tone becomes louder when turned on;
Comparing the product board of the test customer to TI's development board, there is some difference in CP pin signal, and the difference in frequency and amplitude between the CP pin of the oscilloscope AC test product board and the development board is large. Help to see why;
Test conditions:
1, 6 PWM hardware disconnected from the MCU output of the product board, boost from LM5155 to 24V power supply, unconnected motor, Internal BUCK output software disable (measured around 0.57V, is it OK? Not disabled is 3.3V, but the built-in LDO is measured at 3.3V, LDO defaults to the chip's internal draw from BUCK, BUCK output is 0.57V, LDO output should not exceed 0.57V, which is another problematic point that needs to be addressed)
2, the development board is bare board test, disconnected MCU and motor, by independent DC adjustable power supply;
this scope is customer's board,
this scope is 8316EVM
The follow scope : DRVOFF is low
the follow scope :DRVOFF is high.
the schematic is as follow:
