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BQ24133: Recommendation for 12V-12V DC/DC UPS with Li-Ion batteries

Vineet Kumar
Prodigy 70 points
Part Number: BQ24133

Looking for a recommendation on 12V-12V DC-DC UPS with 2-cell Li-Ion batteries.
Output current will be 1-2A.

I have looked at BQ24133. Just wanted to check if it is correct and if there are better alternatives.

  • 0
    TI__Expert 8690 points

    Hi Vineet,

    Can you explain a little bit more on the application for this battery charger?

    For your application you want the output of the DC/DC converter to be the same as the input using a 2 cell battery? This would require the input to buck down to a 2 cell li-ion battery and then boost the battery voltage up to 12V again, this way, if there is any transient on the input, it will not be reflected on the output, as the boost converter is a separate system from the charger (the output will always be 12V regardless of input voltage or battery voltage). The input of the boost converter will have to be connected on the same net as the battery voltage.

    In any case, if you are looking to buck down from a 12V input to charge a 2 cell battery, then bq24133 is the right choice for 2A charging.

    How much does the input voltage vary? Since this is a buck converter, input voltage should not go any lower than ~8.8V to maintain a good margin for duty cycle at about 95% (8.4V max battery voltage output for the buck converter).

    Regards,
    Steven

  • 0 in reply to Steven Bangdiwala
    Prodigy 70 points
    This is a UPS for 12 V pico projectors. I will input the AC adaptor in the device and give the output to the device. In case of a power failure the batteries in the device should be able to supply 12V to the projector.

    Do I need to add 8.4V to 12V boost convertor to BQ24133?
    I am sorry if this is a silly questions.
  • 0 in reply to Vineet Kumar
    TI__Expert 8690 points
    Vineet,

    Yes you will need to add a boost converter to the battery, preferably place it at SRP so that charging current can still be regulated (figure 22 of page 29 on the datasheet). If efficiency is not an issue, you can connect the system directly to the output of the boost converter.

    Regards,
    Steven