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DRV8353: DRV 8353 will detect any error if sensor is not working?

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Part Number: DRV8353

Hi ,

I have an Application of Hall sensor based  BLDC motor drive so i have planning to use MSP430 with DRV8353S smart gate driver, while running the motor or any situation if Hall sensor get fails will this DRV8353 will indicate any fault during that time?

  • Hello Shishod,

    In short, the DRV8353 doesn't have any inherit faults to detect hall failures. However, we know that failing halls with result in lower speeds than expected. So, if the MCU can detect the current speed and measure it by an expected speed, a fault could be detected on the MCU side.

    Detailed Explaination:

    Unfortunately, there is no inherent fault linked to the hall sensors failing. Specifically, the DRV8353 has Current Sense Overrcurrent Protection, VDS monitoring, Gate Drive, UVLO, and Over temperature fault sensing capability.

    So we do have some idea of what will happen when the hall sensor "fails". When a hall sensor "fails" we can assume that the integrated amplifier (or comparator) will fail to output the correct value and output GND, the voltage used pull up the hall signals (HALLPWR), or maybe something in-between. Either way, the signal will show up to the input of the PWM pin and then compared against the VIH and VIL specs.

    This "0" or "1" input is then compared against the values in table 3 which will then determine the state. This state will try to commutate the motor, incorrectly, and we'd expect the motor to get stuck in a state or put in an incorrect state. The end result is a change is speed (all the way to 0 or maybe something below the expected). So, this means you would need to implement something that detects speed and put logic in the MCU to detect an unexpected speed.

    As mentioned in the other E2E, you could route the signals to the MCU directly (and write the code that copies the output of the halls to the input PWM signals of the DRV8353) so the MCU would know the speed by measuring the frequency of the hall inputs. Otherwise, the DRV8353 does have the integrated current sense so you could measure the zero crossings of current from any of the SOx pins into an ADC of the MCU and then derive speed from the frequency of zero crossings. Then, you could make a threshold, if the speed drops below a certain threshold, stop driving the motor (turn on BRAKE pin or maybe ENABLE).

    Best,

    -Cole

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