• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 63 subscribers
  • Views 463 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS65721 not charging battery and not shutting down

James Hutzley
Prodigy 10 points
Other Parts Discussed in Thread: TPS65721

Hello,

I am having a problem with my TPS65721 PMU on my own custom board not charging my 3.7V 500mAh Li-po battery. I have tried 3 different RIset values at 1k, 1.5k, and 3.3k and see no difference. The charge current is measuring in the micro-amps and will only charge the battery about 100mV if left charging overnight. I have reviewed my schematic and layout and do not see any issues. I have tested multiple batteries to ensure that it is not my battery causing the problem.

I am also having a problem where the PMU will not shut down DCDC or LDO. In attempt to turn the LDO and DCDC regulators off, after PB_IN is released high, HOLD_DCDC1 and HOLD_LDO1pins are pulled low. When this happens, the DCDC regulator drops from 3.3V to 1.8V and the LDO drops from 1.8V to 0.6V. I am under the impression that the voltages should both be at 0V.

Let me know if anyone has experienced the same issues.

Regards,

-James 

  • 0
    TI__Genius 16870 points

    Hi James, 

    Yes, the HOLD_DCDC and HOLD_LDO pins should enable and disable the rails after the PB_IN is pressed then released. Both rails should regulate to 0V after the disabling from the HOLD pins. The only exception to this is if you set the HOLD_DCDC bit and HOLD_LDO bit via I2C. Then these bits can be used to enable and disable the rails too like the HOLD_DCDC/LDO pins. 

    As for the battery charging issue, try read register x01 via I2C. If bit 3 is a '1' then the device is reporting that charging is occurring otherwise it is not charging. You can also check bit 2 of the same register if bit 3 is '0'. Bit 2 reports if there is a valid power source to charge from. Finally, you should read register x02 bit 0 or CH_EN. If this is '1' then battery charging is enabled. 

    • What is KISET and IPRECHG?
    • What is the voltage at the battery? 
    Another suggestion is to order an EVM and conduct the same tests on the EVM to ensure that the testing is done correctly. You can order an EVM here. http://www.ti.com/tool/tps65721evm-516