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BQ25895 -- Issue with Schematic

Pradhan Rivankar
Expert 1080 points

Dear Sir /Madam

PFA schematics of my design, we have made the PCB board and test it, but we having following query

(1)we can used default condition of , We can not getting more then 2A output cirrent

(3) When i am give the input voltage 9V/12V, then my output voltage change from 5V to input voltage (9V/12V).

We required 5V/3A output, when input voltage is 9V/12V.

Kindly help to give your inputs on above. Attached is the schematic for your reference.

Thanks and regards

Pradhan

2161.MSIPL PB V1.0_.pdf

  • 0
    TI__Guru**** 217607 points
    Moving this to the Battery Management - Chargers Forum.

    Regards,
    Ryan
  • 0
    TI__Expert 8230 points

    Hello Pradhan,

    Please refer to my comments on the other thread.

    Thanks.

  • 0 in reply to Fernando Lopez
    TI__Guru**** 166886 points

    The PMID pin only provides 5V when in OTG boost mode during which no voltage is applied to VBUS.  The battery provides the power to the boost converter in order to provide the 5V rail.  When a voltage is applied to VBUS, it will be applied to PMID as there is a FET that connects VBUS to PMID.

  • 0 in reply to Jeff F
    Expert 1080 points

    Dear Jeff

    how are you?

    I would also like to know below .

    • What is the peak efficiency of ic for getting 5V/3A on PMID pin? because we have to require still continuous 5V/3A load on PMID Pin.
    • My device efficiency is 78% at 5V/1A load on PMID pin. If i increased load to 1.5 then output will be fluctuated and > 2A load my boost converter off.
    • We use standalone mode of device where switching frequency is 500kHz. and  HIZ mode is disable. is it possible to give 5V/3A on PMID with this default parameter ?

    Thanks for understanding.

    Regards

    Pradhan

  • 0 in reply to Pradhan Rivankar
    TI__Guru**** 166886 points
    Datasheet figure 3 shows boost efficiency at VBAT = 3.2V and VBAT =3.8V. This efficiency curve was taken with an external diode from SW to PMID has been installed to boost efficiency and IHLP-2525CZ 2.2uH inductor with only 18mohm of DSR. 78% seems low even at the lowest VBAT voltage. What is your inductor's DCR and saturation current?

    Switching frequency is only a factor during light load. With higher performance inductor and external Schottky diode, you should be able to get 5V/3A for battery voltages down to V(BAT) = V(OTG_BAT) = 2.9V.
  • 0 in reply to Jeff F
    Expert 1080 points

    Dear Jeff

    We used Schottky diode on SW to PMID pin. Parts number - NSR10F20NXT5G.

    Inductor parts number -  IHLP-2525CZER2R2M01 2.2uH

    DCR = 15.7 to 16.5

    saturation Current - 7.0 A

     

    Pls see below attached Datasheet . Please help to advice.

    regards

    Pradhan

    IHLP2525CZER2R2M01 Inductor.pdf