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CSD97394Q4M Issue - Module Will Intermittently Cease Functioning

A. Rebel
Genius 11740 points

As the subject notes, a client of mine is having an issue where the module will cease functioning randomly and then resume regular function randomly.

The client found that this issue seems to be caused by holding PWM (pin 8) high during start up. Start up is where Vcc is being ramped up, and SKIP# (pin 1) connected to Vdd. The device seem to enter undefined state.

The client found that to solve this issue, holding PWM (pin 8) in tristate, until Vcc is stable, the issue seems to go away.

Is this expected behavior?

  • TI__Mastermind 18200 points
    I am looking into this currently.
  • in reply to Brett Barr1
    TI__Mastermind 18200 points
    Yes, I confirmed with the applications team that this can cause an issue. PWM should either be left floating or tied to ground.

    Also got this response :
    First, please check if the power stage VDD pin is connected to Vcc or Vdd, if power stage VDD pin and SKIP# are connected to different power signals, make sure SKIP# is not tri-state during driver start-up.

    Second, we suggest to start the driver after Power Stage VDD is stable, specifically, controller sends normal PWM signal to Power Stage after Power Stage VDD voltage is stable to guarantee the safe operation of the system; before that, PWM Tri-state is preferred.