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TPS65070 cannot be re-powered by PB_IN=0 after POWER_ON removed, when USB 5V is applied

JH Lin
Prodigy 10 points
Other Parts Discussed in Thread: TPS65070

Hi,

We are using the TPS65070 in a battery powered system, which provides USB charging function. And when the USB is connected charging the battery, and then processor turns off the power by release the POWER_ON pin to floating (which is kept high when System is awake). After that, the system is unable to power up again. We've investigated and found that the VCORE (1.8V) is unable to be up, so is the processor core.

We were thinking that if this scenario is valid or not. That is, when USB power is applied, which keeps the SYS powered, then the registers of TPS65070 will not be reset on the next powering up sequence initiated by asserting PB_IN=0. And in the meantime, VIO(3.3V) is removed, so there's no pull up source for the SCLK and SDAT, and the registers of TPS65070 corrupt. Which , we guess,  causes the abnormality of the VCORE when asserting PB_IN=0 again.

Thanks..

BR

JH Lin 

  • 0
    TI__Genius 16870 points

    JH, 

    Try giving POWER_ON a pull down to GND instead of floating the pin. If they does not help please, monitor VSYS, VCORE, POWER_ON, PB_IN, VUSB and VBAT. Verify where you are at in the State Machine on page 34 in the datasheet. Can you send me scope shots of exactly where you deviate form the state machine if, you do?