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DRV2605: device unexpectedly activating at startup

pseudoguy
Prodigy 80 points
Part Number: DRV2605

We are having an issue with DRV2605s unexpectedly turning on at full strength when the power rail is initialized. The DRV can be completely disconnected from I2C and this will still occur. We have multiple DRV2605s on this power rail, and some have this problem while others do not - some even have it sporadically, and occasionally turn on at startup. 

The power rail is operating at 3.6Vdd. We're wondering if this might be happening because the power rail climbs to this voltage too slowly at startup, as there's a note in the DRV2605 datasheet brownout protection section that mentions the device falling into an "unknown state" if the Vdd rise is slower than 3.6kV/s. If this is the case, what can we do to prevent it? Note that if the devices are connected to a table power supply at the same voltage, they do not experience the issue. 

Thanks!

  • 0
    TI__Expert 8711 points
    Hello,

    Is this for the DRV2605L device? The DRV2605L device has the brownout protection requirements, not the DRV2605 device.
    It is possible that the device is coming up in an unknown state when the VDD ramps too slowly. If that unknown state has the device being pulled out of standby mode and also activating the GO bit, then the device could startup on power-up. One way to check if this is the problem is to connect to I2C and see if the devices are responding when you send commands to the I2C address.
    The only way to prevent this type of action is to make your power rail ramp at the specified rate. I think this could be achieved by adding a load switch between the battery and the devices.