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TPS25750: Impliment BQ25792 Configuration On Demand

Jesse Mills
Prodigy 155 points
Part Number: TPS25750
Other Parts Discussed in Thread: BQ25792, TPS25751

Hello,

I have a design I am working on that uses the TPS25750 as the PD negotiator in several different design configurations. In one configuration, there is no BQ25792 charger module on the i2cm line, however the USB port has a USB source plugged into it. 

After some period of time, a BQ25792 is added to the i2cm line. I have a processor that will know when the BQ25792 is added to the i2cm line, and can communicate to the TPS25750 via i2cs. Is there a way the processor can inform the TPS25750 that the BQ25792 is ready to be configured, or is there some kind of reset that can be triggered by the processor via i2cs?

Thanks

Jesse

  • 0
    TI__Genius 16370 points

    Unfortunately, there's no way to trigger a reinitialization/reboot of TPS25750 that could be initiated from the processor - I2Cw/I2Cr commands are available for additional flexibility, but those may not fit your usecase as TPS25750 would have assumed that BQ is not available in the system and skipped the initialization (at boot-time) 'coz of the NAKs from I2Cs.

    Could TPS25750 be power cycled externally (via VIN3V3 cycle)?

  • 0 in reply to Praneet Kumar
    Prodigy 155 points

    Hi Praneet,

    Thanks for the reply. Yes we can impliment that. Does cycling VIN3V3 reboot/restart the TPS module, even if VBUS is connected?

  • 0 in reply to Jesse Mills
    Prodigy 155 points

    I did test this myself on our prototype. A PD contract was implemented, 3V3-VIN power was removed. It does seem like the TPS module enters some kind of reset:

    This reset only seems to occur once however. If I power cycle the 3V3-VIN power supply again, the reset does not re-occur. Is this because this device is now in 'dead battery' mode, and I need to clear the dead battery flag?

    Also, does this reset result in the TPS module re-implementing its boot sequence?

    Thanks

    Jesse

  • 0 in reply to Jesse Mills
    TI__Genius 16370 points

    You're right - We don't trigger the reset if the device is in dead-battery. Yes, this reset results in the device restarting the boot sequence.

  • 0 in reply to Praneet Kumar
    Prodigy 155 points

    Thanks Praneet. Just a heads up I did in fact find a 'reset' 4CC command - 'GAID'. This clears SRAM and implements a reset on the TPS controller:

    However this command is not defined in and TPS25750 or TPS25751 documentation. Is there any kind of document available that completely documents all possible 4CC commands to this controller?

    Thanks

    Jesse

  • 0 in reply to Jesse Mills
    Prodigy 155 points

    What I said before was actually incorrect, this 'GAID' and 'gaid' command are defined in the TPS25751 technical manual:

     

  • 0 in reply to Jesse Mills
    TI__Genius 16370 points

    You're right - GAID is available on some variants of the device to cold-start the PD controller, but I didn't suggest that as its not exposed on all devices and the behavior on such devices is undefined.