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BQ24610: Power path battery voltage boost configuration

Part Number: BQ24610
Other Parts Discussed in Thread: , BQ25750

Hi TI,

I am designing a medical device, and I am considering using the BQ24610 charger. Is this part recommended for new designs?

The battery configuration is Li-ion 3S2P with 11.1V nominal, 7Ah capacity.

The power supply voltage, input to the charger, is 24V 225W.

The charger circuit with power path must be able to charge the battery at 2 AMPS, and also supply up to 6A to the system at 24 V.

If the power supply is not connected, the battery must be able to supply 6A to the system at 24V; though the battery voltage is only up to 11.1V.

I am planning to use the LM5123 boost IC to boost the battery voltage to 24V to drive the system if the AC is disconnected.

Should the boost circuit be placed in the Drain or Source of the BQ24610EVM BATDRV charger MOSFET?

Should I include additional MOSFETs to input and output of the boost circuit to be controlled if the AC voltage is disconnected?

I also have the option to use a power supply 15V, 225W power supply.

With this option, the boost circuit would always be used regardless if AC is connected or not.

I think this is a simpler solution, but I don't know if it would be recommended.

Does TI have Field Application Engineers (FAE) which could assist in this power design?

Thanks,

Rafael

  • Hello Rafael,

    Thank you for reaching out. 

    Do you need a standalone device or are you open to I2C/SMBus controlled devices?

    Best Regards,

    Christian

  • Hi Christian,

    I think that as long as I can set the input current/voltage, output current/voltage, etc. using passive components, the I2C/SMBus interface could be an optional feature to the charger.

    I was considering the BQ25750, but I received a defective EVM and there were no more in stock for replacement. The high cell count capability and I2C interface isn't necessary, so I thought about using a simpler standalone solution instead. If this or other option is more recommended, then I would consider it again.

    Thanks,

    Rafael 

  • Hello Rafael,

    I think BQ24610 would be your option. I linked a similar E2E question where I showed where the boost convertor should go. I have not tested this design and this is not a typical design, so I can not guarantee that this design will work.

    Previous Post:Boost

    Best Regards,

    Christian.

  • Hi Christian,

    THanks for the BQ24610 confirmation.

    For the Boost positioning, I am worried that the boost circuit will draw current from the battery while the unit is off, correct?

    Perhaps we can introduce a transistor between the BAT+ and the boost circuit, driven by the BATDRV as well? With the intent of disconnecting the boost circuit from the battery while unit is off.

    best regards,

    Rafael

  • Hello Rafael,

    Perhaps we can introduce a transistor between the BAT+ and the boost circuit, driven by the BATDRV as well? With the intent of disconnecting the boost circuit from the battery while unit is off.

    The BATDRV should be able to drive both MOSFETS, but this is not something we have tested. This is something you would have to test.

    Best Regards,

    Christian.