• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 254 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

BQ24773: Force charging without a valid #BATPRES input

Kevin Makovy1
Prodigy 140 points
Part Number: BQ24773

Hello,

I have a battery connected - but its voltage is below the #BATPRES "threshold".  Threshold set at 3 V - battery is currently 2.85 V.

From the pin configuration table of the datasheet it looks like charging is still possible:

Host can enable IDPM and charge through SMBus/I2C when BATPRES is HIGH.

Is there any more data on this - or do I really only need to enable IDPM in ChargeOption0 register then I should be able to charge again?

Thanks for the help,

Kevin

  • 0
    TI__Genius 11850 points

    Hi Kevin,

    • I think there's a bit of a misunderstanding here. The /BATPRES pin is not connected directly to VBAT. Some battery packs have an output pin which can be conveniently connected to /BATPRES on the BQ24773. When the battery pack is plugged in, this pulls the /BATPRES pin low, which indicates to the BQ24773 that the battery is present. If you are not using the /BATPRES functionality, then you should tie the /BATPRES pin to GND.
    • The /BATPRES pin is used to detect battery removal (/BATPRES low to high transition). The /BATPRES low to high threshold is about 2.2 V, as shown below. When the /BATPRES pin is pulled high, the BQ24773 disables charge, exits LEARN mode, and resets the MaxChargeVoltage() and ChargeCurrent() registers. However, the host MCU can still re-enable charge by reconfiguring the registers, even with /BATPRES high.

    • When VBAT is low (VBAT < BATLOWV for 1s charging, or VBAT < MinSystemVoltage() for 2s-4s charging), the BQ24773 can still charge the battery in pre-charge mode. In this state, the charge current is clamped below 384 mA. Here are the relevant portions of the EC table which show the thresholds:

    Best regards,

    Angelo

  • 0 in reply to Angelo Zhang87
    Prodigy 140 points

    Great - thank you for the clarification Angelo.

    -Kevin