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BQ24295 BOOST Disable

Evan Price
Prodigy 20 points
Other Parts Discussed in Thread: BQ24295, BQ24296

Hello,  I am wondering if I will damage the BQ24295 if I choose not to use the internal Boost(and all surrounding discretes).  All I want to do is Have the features of the charge at 3 amp.  Also, if there is a chip with only the charge features it would be greatly appreciated.

Thanks,

Evan

  • 0
    TI__Guru**** 165856 points
    You will not damage the IC by not using the boost converter feature. I am uncertain as to which external discrete components you want to eliminate. Can you explain? Also, the sister device, bq24296, might be a better fit. It has the same boost function but does not automatically turn on boost and requires a smaller capacitor on PMID.
  • 0 in reply to Jeff F
    Prodigy 20 points

    Great thank you for your prompt response!  I think I have used some wrong terminology. I am simply planning on leaving SYS, SW, and BTST disconnected and not providing a system voltage, which is being supplied by other means.  Thus, the "unnecessary" discretes would be L1, C3, C6,C7 per the diagram at the top of the BQ24295 datasheet.

    Thanks,

    Evan

  • 0 in reply to Evan Price
    TI__Guru**** 165856 points
    The bq24295/6 is a buck switching converter based charger. It requires all of those components if you do not connect a system load to SYS. The BTST capacitor is used to provide a "boosted" voltage to provide the buck converter's high side N-FET. The BOOST feature to which I was referring is the charger's ability to operate the buck converter in reverse as a boost converter and provide a 5V output at VUSB, using the battery as the power source. All of TI's 3-A charger's are switching based and have the SYS output.
  • 0 in reply to Jeff F
    Prodigy 40 points

    Jeff F said:
    You will not damage the IC by not using the boost converter feature. I am uncertain as to which external discrete components you want to eliminate. Can you explain?

    If one were to turn off the boost converter feature and never use it (for example through registers or by grounding the OTG pin), can the capacitors on PMID be safely omitted?