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BQ25620: Battery Charger with constant Output voltage in Battery Only Mode

Part Number: BQ25620


For our application, we require the output from battery to power a PMIC which takes input from 3.3V to 5V. Battery voltage is 3.7V, which will drop overtime.

So we are looking for a battery charger IC with constant output voltage in battery only mode.

I was looking at BQ25620, but it seems that the output voltage at SYS pin is only adjustable in VBUS mode. Is this understanding correct?

Or can we make some register settings to provide constant output voltage in battery only mode?

Does TI have any IC with Battery charger + Buck-Boost converter integrated? The alternative solution we have to go with is Charger + Boost converter -> 2 separate IC's, but we prefer an integrated solution if available.

Please suggest.

Thanks & Regards,


  • Hi Pavan,

    Buck switching converters with NVDC architecture like BQ25620 only turn on the FET to connect BAT to SYS when no power is present at VBUS.  That means that SYS follows BAT down as it discharges. TI doesn't and to my knowledge even our competitors don't have a 2 switch buck switching converter that also has a buck-boost converter (needing 4 more switches and 2nd inductor) to provide a regulated output at SYS.  

    A boost (or SEPIC) or buck-boost converter following the SYS output is likely your best option.



  • Thanks for the Reply. It seems Buck-Boost following SYS output is what we will have to go with.