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How to turn off TPS65720

Sairam Kishore badireddi
Prodigy 100 points
Other Parts Discussed in Thread: TPS65720, BQ27421-G1

Hi,

CAn any one let me know how to shut down the TPS65720 once it is turned on  once the PB_IN is pressed and both DCDC and LDO are turned on by setting the hold bits through I2C.

As there is no Key out going to MCU to identify the key pressed again for turning it off how can I detect the second push botton press for turning it off.

I have gone through the data sheet and there is Push button interrupt which I can poll to detect it. Upon this detection, can I change the hold register value to turn off both the LDO and DCDC. Please clarify

Regards,

Kishore.

  • 0
    TI__Genius 17380 points

    Hi Kishore,

    You should be able to unmask PB_STAT in the IRMASK2 register to generate an interrupt when pushbutton is pressed or poll the PB_STAT bit in the CONTROL1 register. To turn off, just clear the HOLD bits and it will turn off when PB is released.

  • 0 in reply to Kevin LaRosa
    Prodigy 100 points

    Hi Kevin,

    Thanks for the prompt reply.

    Can you also please clarify on configuration problems we are facing in using TPS65720 for our design.

    To turn on the module  from battery, Is the HOLD_DCDC1 and HOLD_LDO1 pulled high for retaining it after PB_IN is released.

    And for turning it OFF, can the MCU drive the HOLD_DCDC1 and HOLD_LDO1  pins LOW, because setting only the HOLD bits will not help us as they are logically OR'd.

    Can we identify a long press  by integrating PB_STAT interrupt and polling of PB_STAT in the CONTROL1 register.

    And at times if the MCU is stuck or hung in undetermined state, is there a way to switch off the PMIC or need to wait for the entire duration for the battery to get drained OFF and restart it by plugging the USB IN where the MCU gets reprogrammed from FLASH and start working normally.

    Can the  BQ27421 integrated with TPS65720 to get fuel gauge information for a 100mAH battery.

    Regards,

    Kishore.

  • 0 in reply to Sairam Kishore badireddi
    TI__Genius 17380 points
    Hi Kishore,

    There are several different ways you can implement your control scheme. Based on your comments above, my favorite way to implement would be to not use the I2C bits but to have MCU pull up the HOLD pins. Then, if MCU becomes stuck, you can have a reset pushbutton between HOLD pins and GND that forces the hold pins to GND to disable DCDC1 and LDO1. You could even implement circuitry for long key press and use the same button as the power on button using RC time constants and a couple FETs.

    I don't see any reason the BQ27421-G1 couldn't be used with the TPS65720, though I'm not an expert on the BQ27421-G1. You may want to post to the battery charging forum if you are concerned. e2e.ti.com/.../180