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Original question:

bq25892 / Default register setting input Current Limit

BQ25892: bq25892 / Default register setting input Current Limit & Default charge current

manish singh64
Prodigy 70 points
Part Number: BQ25892

Hi E2E team

Q1) We are using BQ25892 fast Charging  IC  for charge 4000mAH battery ,

we are facing the issue with default charge current 2.048,we cant achieve.

Our pin setting is:-

Case 1) input 5V/3A

  1. PSEL -LOW

  2. OTG- LOW

  3. ILIM-130K BETWEEN ILIM AND GROUND.

  4. TS- 3.24K BETWEEN REGN AND 30.1K+10K TRIM POT BETWEEN TS AND AGND .

  5. QON-NOT USE.

Case 2) input 5V/3A

  1. PSEL -LOW

  2. OTG- LOW

  3. LIM-130K BETWEEN ILIM AND GROUND.

  4. TS- NO THERMISTOR CONNECTION WE USE 10K &10K BETWEEN REGN AND GROUND.

  5. QON-NOT USE.

Q1) IS BEHAVIOR OF BQ25892 CHANGE IF WE USE NO THERMISTOR CONNECTION ?

INPUT- 5V/3A

Q2) WE ACHIEVE   Vbat- 4.170V/450mA to 230 mA.

                                 Vsys- 4.213V

WHY WE CANT ACHIEVE 2.048A DEFAULT CURRENT ?

  • 0
    TI__Guru**** 166996 points
    Hi Manish,

    For ILIM=130k do you mean 130 ohm? Are you disabling the ILIM pin in the I2C register? Do you have access to the charger's I2C status registers? If so, they will tell you what is limiting the current? Things that could be limiting the charge current are: too much load on system, VINDPM engaged because voltage at VBUS has drooped too low due to high resistive path from supply.
  • 0 in reply to Jeff F
    Prodigy 70 points

    Hi jeff

    Q1)For ILIM=130k do you mean 130 ohm? 

      Yes , we are using 130 ohm.

    Q2)Are you disabling the ILIM pin in the I2C register?

        NO , We are using BQ25892 IC in standalone(RC-Settable)

    Q3)Do you have access to the charger's I2C status registers? 

         NO , We have not access I2C status register 

    Q4)Things that could be limiting the charge current are: too much load on system

           we are using BQ25892 in low power device , our maximum current consumption is below 400mA.

  • 0 in reply to manish singh64
    TI__Guru**** 166996 points
    What is the voltage measured at the VBUS pin and GND? That is the voltage at REGN? If you have a current meter in series between the BAT pin and battery, please remove it (or short it out).
  • 0 in reply to Jeff F
    Prodigy 70 points
    Good morning Jeff
    5.150V at VBUS pin and GND, yes same at REGN pin , ok i have short battery directly with BAT pin.
    we have calculate 300mA at VBUS.

    So Jeff tell me how to use BQ25892 IC in standalone mode and how we achieve 2.046A default battery charge current?
  • 0 in reply to manish singh64
    Prodigy 70 points
    Good morning Jeff
    5.150V at VBUS pin and GND, yes same at REGN pin , ok i have short battery directly with BAT pin.
    we have calculate 300mA at VBUS.

    So Jeff tell me how to use BQ25892 IC in standalone mode and how we achieve 2.046A default battery charge current?
  • 0 in reply to manish singh64
    TI__Guru**** 166996 points
    If VBAT is below 4.2V, VBUS is only limited by the lower of ILIM pin resistor or IINDPM setting which should be 3A if PSEL is low, unless VBUS has dropped below the VINDPM threshold. With input current at max and low load on SYS, the charger will charge at 2A in standalone mode.