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BQ24702: Regarding BQ24702 user's guide, how to detect Li+ or Ni-MH

Shinichi Inoue
Guru 20281 points
Part Number: BQ24702
Other Parts Discussed in Thread: BQ25703A, BQ2000, BQ24133

Dear Specialists,

My customer is considering BQ24702 and has a question.

I would be grateful if you could advise.

---

I have questions regarding BQ24702 user's guide.(SLUU160A)

1. Which pin of the IC does detect Ni - MH battery or Li - ion battery?

2. How does the device select the EOC battery voltage setting (the series number of batteries)?

---

I appreciate your great help in advance.

Best regards,

Shinichi

  • 0
    TI__Genius 11850 points

    Hi Shinichi,

    The BQ24702 sets the battery charge voltage through the BATSET pin. Please see the description on page 13 of the datasheet for more details, as well as the "Setting the battery charge regulation voltage" section on pages 17-18.

    However, the BQ24702 is not suitable for charging NiMH batteries. The parametrics table above shows that the charger is only designed for use with Li-ion/Li-Polymer batteries. This is because the BQ24702 is a standalone device which does not have an I2C or SMBus interface to reconfigure various settings and handle termination, which should be treated differently than with Li-ion batteries. This thread provides some more information on NiMH charging: e2e.ti.com/.../2749743

    If your customer would like to charge both Li-ion and NiMH batteries, then a host-controlled device would be more suitable. If you give me more information about your customer's application and required parameters, then I can help suggest some alternative chargers that would work.

    Best Regards,

    Angelo

  • 0 in reply to Angelo Zhang87
    Guru 20281 points

    Hi Angelo,

    Thank you for your reply.

    I'll share your suggestion with the customer.

    When I get theor information, I'll send to you.

    I appreciate your great help.

    Best regards,

    Shinichi

  • 0 in reply to Shinichi Inoue
    Guru 20281 points
    Hi Angelo,

    The customer 's condition

    Li+ is 3sell and sells of NiMH is similar voltage as Li+ .
    They are looking for a standalone charger that can use both types.
    The charging profile of NiMH has not been decided yet, so any type can suggest.

    Is there any usable standalone device ?

    I appreciate your great help.
    Best regares,
    Shinichi
  • 0 in reply to Shinichi Inoue
    Guru 20281 points
    Hi Angelo,

    The requirements changed a little.

    Li+ 2sell and NiMH 4/6/8sell(4.8/7.2/9.6V)

    Are there any standalone devices that can be charged?

    I appreciate your great help.

    Best regards,
    Shinichi
  • 0 in reply to Shinichi Inoue
    TI__Genius 11850 points
    Hi Shinichi,

    Due to the different requirements for Li-ion and NiMH charging, a standalone device would not be practical for handling both types of batteries. A host-controlled device such as the BQ25703A would be more suitable for your customer's application. It uses an I2C interface and can charge both Li-ion and NiMH up to your customer's voltage requirements.

    If your customer is opposed to using a host-controlled device, then another option would be to use two standalone chargers, one for each battery chemistry. For example, the BQ24133 could be used to charge Li-ion, and the BQ2000 could be used to charge NiMH. While the BQ2000 could be used to charge both Li-ion and NiMH batteries, it's an older part, and we recommend a newer device for charging Li-ion batteries.

    Best Regards,
    Angelo
  • 0 in reply to Angelo Zhang87
    Guru 20281 points
    Hi Angelo,

    Thank you for your reply.

    I'll talk your answer with the customer.

    If he has an additional question, I cousult you again.

    Best regards,
    Shinichi