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Looking for Battery Management IC

Jonathan Anderson
Prodigy 160 points
Other Parts Discussed in Thread: TPS54531, BQ24610

Hi

I would like to get recommendation on what Battery Management IC is fit for application purpose.

Looking for something that will allow end user to plug in any adapter from 5 to 28 volts and output 5 volts and 5 amps without blowing up for MCU which already has its own power management but no charging capabilities.

We were looking at using a BQ24610 and TPS54531  in front of system load and feeding a gas gauge I2C to MCU to calculate battery percentage ?

power path is definitely a feature we want.

Thanks,

J

  • 0
    TI__Mastermind 24075 points

    H Jonathan,

      BQ24610 has direct powerpath feature through the use of an integrated BATDRV, that drives a PFET between BAT and SYS. The downside to direct powerpath is that SYS will tie either to input voltage, or battery voltage, so you can configure the TPS54531 in front of the system load if you require a regulated SYS voltage rail.

    BQ24610 can accept 5V - 28V, however as it is a buck charger, it requires an input voltage higher than the output voltage. The minimum threshold is defined as the SLEEP threshold, so keep this in mind when choosing input adapter and charge regulation voltage for your battery. I have not seen 5V output as a requirement before, as usually battery voltage requirement for single cell Li-ion is around 4.2V.

    BQ24610 can achieve 5A charging.

    Regarding gas/fuel gauge you can take a look at our portfolio here: http://www.ti.com/power-management/battery-management/fuel-gauges/overview.html and direct a new E2E post with the relevant part number, and the expert in charge of those parts can answer any questions you have

  • 0 in reply to Kedar Manishankar
    Prodigy 160 points

    Hey

    So adapter voltage needs to be higher than SRN voltage to trigger  powerpath to select input source ?

    so my understanding is when the battery is under maximum battery voltage and over minimum battery voltage than it is with in the wake threshold to charge battery? and then when battery reaches max voltage then its in the sleep threshold and charger stops charging the battery?

    if the battery is under minimum voltage it would be in wake threshold?

    is this correct?

    ISET1 = charging current when voltage is in between minimum and maximum  battery voltage

    ISET2 = charging current when voltage is under depleted battery voltage

    SRP/SRN = max charging current after reaching max battery voltage

    VFB = charging voltage (max battery voltage?)

    TTC = timer for precharge and fast charger? 5.6nF per minute?

    TS = connects to battery thermistor

    I gather minimum battery cut off voltage and VLOWV is 2.1v and is unchangeable? 

    what value would VRECH be if Regulation Voltage is the battery max voltage?

    are these values automatically calculated by the IC?

    I noticed PG output indicates if VCC voltage is within 5v and 28v? though there wouldn't be able to tell difference between between a fault and not being plugged in?

    one last thing Input Adapter Current Regulation

    as it will have a wide range of voltages, the lower voltages could use more current? should this be set to the maximum current that lowest adapter voltage would use?  

    sorry for all the questions.

    Thanks,

    J

  • 0 in reply to Jonathan Anderson
    TI__Mastermind 24075 points

    Hi Jonathan,

    • Yes, if adapter voltage > battery voltage by SLEEP threshold delta, then ACDRV will be turn on, and BATDRV will be turned off. ACDRV and BATDRV have complementary break before make logic, so conversely if SLEEP is hit, then ACDRV will turn off and BATDRV will turn on
    • This is not correct. Wake time is with respect to the battery absent detection feature. Please refer to 9.3.23 Battery Detection for understanding regarding wake time. SLEEP threshold is only dependent on adapter voltage and battery voltage. When battery is fully charged, then BQ24610 will terminate charge to end the charge cycle, so as to not overcharge the battery. Please refer to figure 14. and section 9.3.5.
    • BQ24610 can charge from deeply discharged battery with precharge current set by ISET2, once VFB>VLOWV then it will charge with fast charge current set by ISET1. Please refer to figure 14. for the typical charging profile. I think there is a misconception regarding wake timer here
    • ISET1 sets fast charge current, when VLOWV < VFB < 2.1V
    • ISET 2 sets precharge current when VFB < VLOWV
    • SRP SRN sense the charge current through the differential voltage sensed on RSR sense resistor between them, and feedback to the IC, so that charge current is accurately regulated during C phase of charging.
    • VFB is the internal reference that corresponds to the battery voltage. (Section 9.3.1)
    • TTC has an equation that corresponds to fast charge safety timer. Refer to TTC INPUT AND SAFETY TIMER from the EC table
    • Internal VFB thresholds are fixed and can't be changed
    • VRECHG = 2.05V
    • Are which values automatically calculated by IC?
    • STAT1 and STAT2 indicate fault condition, but PG indicates if power is good. Active LOW when IC has a valid VCC (not in UVLO or ACOV or SLEEP mode).
    • Input current regulation loop regulates the charge current if input current limit is hit. This depends on type of input adapters used, as if the input adapters have their own current limit, and you set the input current limit of the IC above this, this could cause the input adapter voltage to crash as it cannot supply the output requirements.

    There are a lot of questions covered in the datasheet, so I would recommend reading those sections to get a better understanding. We have a BQ24610 evaluation module (EVM) also available which can be used to physically evaluate the part. I would recommend testing on this before designing your system. 

  • 0 in reply to Kedar Manishankar
    Prodigy 160 points

    Hey

    thank you. I managed to find the calculation tool

    went with a 3.7v battery with Discharge rate at 5C to 10C and going step up the voltage to 5v connected between Q3 and system via a diode.

    and step down converter for adapter connected between Q4 and system via a diode.

    I set the Fastcharge timer to battery charge curve.

    Battery pre-charge/termination current set to 3% of rated charge current.

    Battery Regulation set to 4.2v.

    Adapter voltage 6v-28v.

    how is discharge voltage cut off set? current battery has cut off at 2.75v. guessing its 2.1v?

  • 0 in reply to Jonathan Anderson
    TI__Mastermind 24075 points

    Hi Jonathan,

       BQ24610 does not have configurable cut off mode. It has integrated battery short protection, which is a fast response loop to stop switching in event of a battery short. For cutoff, it is common practice to have this handled by the external gauge or protector. These parts will have the added charge/discharge protection FETs which will turn off at a configurable cutoff point, to disconnect the battery and prevent it from being discharged below cutoff point. You can take a look at the BQ297xx family: https://www.ti.com/lit/ds/symlink/bq2970.pdf?ts=1592343860098&ref_url=https%253A%252F%252Fwww.google.com%252F#:~:text=The%20BQ2970%20device%20provides%20the,high%20charge%20or%20discharge%20currents.&text=These%20features%20are%20implemented%20with%20low%20current%20consumption%20in%20NORMAL%20mode%20operation.

    If I am not mistaken, using these parts could give you a cutoff in the range from 2V to 2.8V,

    For questions regarding the protector, create another post with that part number in it, and the expert regarding those parts will be able to answer any questions you have.