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Battery Charger with power path for IoT device

Aditya Rastogi71
Prodigy 20 points
Other Parts Discussed in Thread: BQ24295, BQ24250, TPS63027, BQ25601, TPS63020

Greetings,

We need a PMIC with following requirements.

1) Input Supply - 12v DC max

2) Output Voltage - 3.3V to 5V (adjustable)

3) Output Current - 2A min

4) Battery will be 1 cell Li-on or LiPo

Currently we are using Bq24295 in one of application problem with that is its 5v o/p viz PMID is connected through FET which sometimes turnoff while switching and thus the controller reboots and creates issue for us.

BQ24250 suits us but its 5v ldo doesnt provides much current to power our core. Our Core has a max consumption of 1.2A on full load. Some other peripherals attached to it increases the consumption to 2A this doesn't includes battery charge current.

We are looking forward for a solution that can also tell us battery potential. Our application is an always running Iot device which requires an power path and battery charger with applicable buck and boost converter.

I hope I have explained everything in understandable way.

Thanks 

Aditya Rastogi

  • 0
    TI__Guru**** 166416 points
    Aditya,

    When powered at VBUS, the buck converter of our power-path battery chargers provide V(SYS) = higher of (VSYSMIN or V(BAT)) where VSYSMIN is typically ~3.6V. Therefore their SYS output voltage is not user adjustable up to 5V. When power is applied at VBUS, the V(PMID) = V(VBUS) - IBUS*RDSONQ1. When VBUS is not applied and OTG is enabled, V(PMID) = 5.xV because the buck converter works in reverse as a boost converter. The maximum output current of bq24295 in OTG mode is 1.5A.

    If the battery is discharged below VSYSMIN, can your system be powered by 3.6V? If not, is it possible to use a buck/boost converter like TPS63027 at SYS to provide 3.3V to 5V from the SYS of a charger like bq25601?
  • 0 in reply to Jeff F
    Prodigy 20 points

    Thanks for the reply Jeff,

    Bq25601 is perfect for our requirement. Just a few things.

    1.  How can the sys voltage be set to 4.6V while in default mode.
    2. In host mode when the system reboots VSYS will be 3.5V always 

    Instead of TPS63027 can you suggest any other part we don't prefer BGA package.  Its counter part with QFN package will work.

    Thanks

  • 0 in reply to Aditya Rastogi71
    TI__Guru**** 166416 points

    Regarding 1 and 2, as I mentioned previously, all of our power path charger's maximum V(SYS) = V(BAT) + 50-150mV, depending on the charger, when the battery voltage is above the VSYS(MIN) voltage.  You cannot set SYS to a fixed voltage.  You can set the minimum V(SYS) between 3.0V-3.7V using the SYS_MIN I2C register.  This is the minimum V(SYS) when the battery is discharged. Below is a graphic illustration.

    Regarding TPS63027 replacement, you can try TPS63020 but it will struggle to provide 5V/2A from 3.0V discharged battery.