BQ25887: BQ25887 Low Current

Sean Kovacs

Part Number: BQ25887

I noticed my BQ25887 eval board, even with PGSEL tied to ground and 374Ohm ILIM resistor, is only outputting 1.3A as measured by my multimeter.

What would cause a lack of current for standalone mode? Would the lack of NTC thermister cause this?

over 2 years ago

0 Michael Emanuel35 over 2 years ago

TI__Mastermind 40425 points

Hello,

Can you please provide a full register dump in the state you are observing?

Regards,

Mike Emanuel

0 Sean Kovacs over 2 years ago in reply to Michael Emanuel35

Prodigy 140 points

Here is the dump with both cells at 4.1v, bench supply running at 5.05v/3A max in CV mode. I realize it shows REG_CHARGER_STATUS_1 in a Taper Charge mode, but rest assure it runs at this current (~1.3A) in 011 (Fast Charge) mode as well. I'll discharge the batteries again and run this same output.

REG_CELL_V_LIMIT(00h):10100000
REG_CHARGE_CURR_LIMIT (01h):01011110
REG_INPUT_V_LIMIT (02h):10000100
REG_INPUT_CURR_LIMIT (03h):00111001
REG_PRECHARGE_N_TERMINATION_CTRL (04h):00100010
REG_CHARGER_CTRL_1 (05h):10011101
REG_CHARGER_CTRL_2 (06h):01111101
REG_CHARGER_CTRL_3 (07h):00000010
REG_CHARGER_CTRL_4 (08h):00001101
REG_ICO_CURR_LIMIT (0Ah):00001010
REG_CHARGER_STATUS_1 (0Bh):00001100
REG_CHARGER_STATUS_2 (0Ch):10110010
REG_NTC_STATUS (0Dh):00000000
REG_FAULT_STATUS (0Eh):00000000
REG_CHARGER_FLAG_1 (0Fh):00000000
REG_CHARGER_FLAG_2 (10h):00000000
REG_FAULT_FLAG (11h):00000000
REG_CHARGER_MASK_1 (12h):01110000
REG_CHARGER_MASK_2 (13h):00000000
REG_FAULT_MASK (14h):00000000
REG_ADC_CTRL (15h):00110000
REG_ADC_FUNCTION_DISABLE (16h):00000000
REG_IBUS_ADC1 (17h):00000000
REG_IBUS_ADC0 (18h):00000000
REG_ICHG_ADC1 (19h):00000000
REG_ICHG_ADC0 (1Ah):00000000
REG_VBUS_ADC1 (1Bh):00000000
REG_VBUS_ADC0 (1Ch):00000000
REG_VBAT_ADC1 (1Dh):00000000
REG_VBAT_ADC0 (1Eh):00000000
REG_VCELLTOP_ADC1 (1Fh):00000000
REG_VCELLTOP_ADC0 (20h):00000000
REG_TS_ADC1 (21h):00000000
REG_TS_ADC0 (22h):00000000
REG_TDIE_ADC1 (23h):00000000
REG_TDIE_ADC0 (24h):00000000
REG_PART_INFO (25h):00101001
REG_VCELLBOT_ADC1 (26h):00000000
REG_VCELLBOT_ADC0 (27h):00000000
REG_CELL_BALANCING_CTRL1 (28h):00101010
REG_CELL_BALANCING_CTRL2 (29h):11110100
REG_CELL_BALANCING_STATUS_N_CNTRL (2Ah):11000000
REG_CELL_BALANCING_FLAG (2Bh):00000000
REG_CELL_BALANCING_MASK (2Ch):00000000

0 Sean Kovacs over 2 years ago in reply to Sean Kovacs

Prodigy 140 points

I ran the batteries down to 7.15v, hooked it up to the same DC power supply. It's currently only pulling 200mA. I turned on the ADC, here is the registry dump for this session. ICO is limiting the current to 500ma. All voltages read normal.

REG_CELL_V_LIMIT (00h):10100000

REG_CHARGE_CURR_LIMIT (01h):01011110

REG_INPUT_V_LIMIT (02h):10000100

REG_INPUT_CURR_LIMIT (03h):00111001

REG_PRECHARGE_N_TERMINATION_CTRL (04h):00100010

REG_CHARGER_CTRL_1 (05h):10011101

REG_CHARGER_CTRL_2 (06h):01111101

REG_CHARGER_CTRL_3 (07h):00000010

REG_CHARGER_CTRL_4 (08h):00001101

REG_ICO_CURR_LIMIT (0Ah):00000000

REG_CHARGER_STATUS_1 (0Bh):00000011

REG_CHARGER_STATUS_2 (0Ch):10110010

REG_NTC_STATUS (0Dh):00000000

REG_FAULT_STATUS (0Eh):00000000

REG_CHARGER_FLAG_1 (0Fh):00000000

REG_CHARGER_FLAG_2 (10h):00000000

REG_FAULT_FLAG (11h):00000000

REG_CHARGER_MASK_1 (12h):00000000

REG_CHARGER_MASK_2 (13h):00000000

REG_FAULT_MASK (14h):00000000

REG_ADC_CTRL (15h):10000000

REG_ADC_FUNCTION_DISABLE (16h):00000000

REG_IBUS_ADC1 (17h):00000000

REG_IBUS_ADC0 (18h):11110111

REG_ICHG_ADC1 (19h):00000000

REG_ICHG_ADC0 (1Ah):00000110

REG_VBUS_ADC1 (1Bh):00010011

REG_VBUS_ADC0 (1Ch):10011111

REG_VBAT_ADC1 (1Dh):00011100

REG_VBAT_ADC0 (1Eh):01111001

REG_VCELLTOP_ADC1 (1Fh):00001110

REG_VCELLTOP_ADC0 (20h):00111000

REG_TS_ADC1 (21h):00000010

REG_TS_ADC0 (22h):00111111

REG_TDIE_ADC1 (23h):00000000

REG_TDIE_ADC0 (24h):01111000

REG_PART_INFO (25h):00101001

REG_VCELLBOT_ADC1 (26h):00001110

REG_VCELLBOT_ADC0 (27h):00100110

REG_CELL_BALANCING_CTRL1 (28h):00101010

REG_CELL_BALANCING_CTRL2 (29h):11110100

REG_CELL_BALANCING_STATUS_N_CNTRL (2Ah):11000000

REG_CELL_BALANCING_FLAG (2Bh):00000000

REG_CELL_BALANCING_MASK (2Ch):00000000

0 Sean Kovacs over 2 years ago in reply to Sean Kovacs

Prodigy 140 points

So I turned on the ADC and noticed this:

REG_IBUS_ADC1 (17h):00000101

REG_IBUS_ADC0 (18h):00001100

Why is the chip only sensing 1.3A current coming from VBUS? I've tried a few different sources - my bench supply, a few different chargers ranging from normal phone USB power sources to quick charge high current USB power sources.

0 Michael Emanuel35 over 2 years ago in reply to Sean Kovacs

TI__Mastermind 40425 points

Hello,

Can you please report the input voltage, input current, top cell voltage, bottom cell voltage, full battery voltage, and charge current as measured by a multimeter? Report all off the status registers for each case you observe. Also, please send a schematic.

Regards,

Mike Emanuel

0 Sean Kovacs over 2 years ago in reply to Michael Emanuel35

Prodigy 140 points

I bought the TI eval board and it seems to be more stable in its operation.

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BQ25887: BQ25887 Low Current