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BQ500412 - V_IN (pin 46)

Zafi Ramarosandratana
Prodigy 100 points
Other Parts Discussed in Thread: BQ500412, TPS61087, TPS54231

Hello,

If I understand correctly, the 5 V interface of the BQ500412 Evaluation Board powers the BQ500412 chip via V_IN and outputs 3.3V on V33D. Is it correct ?

If yes, can I use the same architecture on my design or is it specificto the EVM ?

Thanks,

Zafi.

  • 0
    TI__Genius 14890 points

    Zafi,

    No, 5V does not go directly to the bq500412.  Please look at the EVM schematic in more detail.  The absolute maximum voltage on the V33A and V33D pins  is 3.6V.

    The 5V input goes into the EVM goes to TPS61087 where the voltage is boosted to node Vin.  That voltage goes to the 12V input node past L6.  Vin is the input to the TPS54231 which creates 3.3V on node Vcc.  The Vcc node is tied to V33D and V33A of the bq500412.  The V33D and V33A pins are supplies to the bq500412.

    The architecture chosen here allows for a 5V input or a 12V input.  In a typical end equipment application, only a single voltage is used, which simplifies the design.

    Regards,

    Dick

  • 0 in reply to Dick Stacey
    Prodigy 100 points

    Thanks Dick, got it.

  • 0 in reply to Dick Stacey
    Prodigy 10 points

    Dick, 

    I have another quick question.  If I want to use only a 12V supply, how do I connect pin 46 of the bq500412?  Do I leave it float, like in the application schematic on the TI page?  Or should I connect it like it is stated on the datasheet?

    System input voltage, used for DPL. Use 76.8-kΩ to 10-kΩ divider to minimize quiescent V_IN current

    Thanks in advace

    Torrin

  • 0 in reply to Torrin Santy
    TI__Guru 65836 points

    I will send out more info on this question later.

    The quick answer is yes use 76.8k and 10k divider for pin 46.