BQ25731EVM: Charge current at zero

Jimmy C.

Part Number: BQ25731EVM
Other Parts Discussed in Thread: BQSTUDIO, BQ25731

Tool/software:

Hello,

I am using the evaluation board BQ25731EVM, and I can't find the way to get proper charge current with ChargeCurrent() for my 1s battery. I am reading 0A on the Ammeter on the Vbat line of the battery and the register ADC IBAT always gives 0. On the other hand, the voltage is set properly with ChargeVoltage() at 3,6V (measured on Vbat with a voltmeter).

I have checked the conditions that could lead to a reset of this ChargeCurrent() register:

CELL_BATPRESZ going LOW : 1,5V measured on TP24.
STAT_AC : the Adapter is present, read in ChargerStatus()
RESET_REG asserted : set at 0 in ChargeOption3()
Charge voltage is written to be 0V : set at 3600mV
Watch dog event is triggered : it is disabled in ChargeOption0.

I am basically writing in this order in BQStudio after POR:

ChargeOption0() = 0x070B ; to disable watchdog and the charge
ChargeVoltage() = 0x0E10 ; to set the voltage to 3600mA
ChargeCurrent() = 0x0200 ; to set the current to 1024mA
ChargeOption2() = 0x0077 ; to set input current limit with IIN_DPM register, and set IBAT pin as charge current.
ADCOption() = 0xA0FF ; to enable the ADC operation and channels
ChargeOption0() = 0x070A ; to enable the charge.

Other registers are not changed. However I have tried different registers configuration but I can't point what I am doing wrong.

I have read on other posts that the BQ25731 could reject the settings if the demand is higher than input power. I am using a laboratory stabilized power supply with an output of 10V and 3,2A min. I have also tried with higher voltage at 20V but no effect.

The parameters settings of the BQ25731EVM are as defined inside the datasheet, except for CELL setting placed on JP3(1-2).