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BQ24195 Charger not drawing not more than 500mA

Nigil K
Prodigy 30 points
Other Parts Discussed in Thread: BQ24195, BQ24190

Hi,

We are using BQ24195 for battery charging and power path management. When we plug in 5VDC 2A adapter or 5VDC 2A DC source, we are observing only 500mA. We are using USB cable to charge and the DP and DN are shorted to make it as DCP. As per my understanding DCP should draw up to 1.5A but not getting in our case. Battery voltage measured during this period is 3.7V

Register dump and schematics are attached for reference. ILIM resistor also changed to 330Ohms to set the fast charging current to 1.5A

Please refer the below attachments and advice on what could be wrong.

Thanks and Regards,

Nigil


bq24190 1-006b: bq24190_irq_handler_thread: ZZZZ Read all registers
bq24190 1-006b: bq24190_read: reg = 0x00 data = 0x35 0xd4
bq24190 1-006b: bq24190_read: reg = 0x01 data = 0x1b 0xd4
bq24190 1-006b: bq24190_read: reg = 0x02 data = 0x60 0xd4
bq24190 1-006b: bq24190_read: reg = 0x03 data = 0x11 0xd4
bq24190 1-006b: bq24190_read: reg = 0x04 data = 0xb2 0xd4
bq24190 1-006b: bq24190_read: reg = 0x05 data = 0x8a 0xd4
bq24190 1-006b: bq24190_read: reg = 0x06 data = 0x03 0xd4
bq24190 1-006b: bq24190_read: reg = 0x07 data = 0x4b 0xd4
bq24190 1-006b: bq24190_read: reg = 0x08 data = 0xac 0xd4
bq24190 1-006b: bq24190_read: reg = 0x09 data = 0x00 0xd4
bq24190 1-006b: bq24190_read: reg = 0x0a data = 0x23 0xd4
bq24190 1-006b: bq24190_read: reg = 0x08 data = 0xac 0xd4
bq24190 1-006b: bq24190_charger_get_online: online = 1
bq24190 1-006b: bq24190_read: reg = 0x09 data = 0x00 0xd4
bq24190 1-006b: bq24190_charger_get_health: health = 1
bq24190 1-006b: bq24190_read: reg = 0x08 data = 0xac 0xd1
bq24190 1-006b: bq24190_charger_get_online: online = 1
ltc cap[3289600][65535]
bq24190 1-006b: bq24190_read: reg = 0x08 data = 0xac 0xd0
bq24190 1-006b: bq24190_charger_get_online: online = 1
init: untracked pid 3165 exited

 

  • 0
    TI__Guru**** 165886 points
    Per reg0x08, the charger is in either VINDPM or INDPM. VINDPM means that the input voltage at the VBUS pin has drooped to the input voltage limit setting and so the IC has reduced the input current limit to prevent the input source from crashing. INDPM means that the IC has reached the input current limit and cannot provide the requested charge current plus system current. Based on your register settings, input current limit was properly set to the lower of the D+/D- 1.5A or ILIM resistor value of 1.6A. The charge current appears to be the default of 2.048A. What is the voltage at the VBUS pins? Is there too much voltage drop across your USB cable?
  • 0 in reply to Jeff F
    Prodigy 30 points

    Hi Jeff,

    Thanks for your response. We are using an external DC source which is set at 5VDC 3A capacity. We are not seeing any dip in voltage there.

    One thing we observed is the voltage at ILIM pin is 0.5V. As per my understanding it should be 1V I guess. Is that the reason why we are getting less charging current? What is the expected voltage at ILIM pin at different charging conditions? 

    Thanks and Regards,

    Nigil

  • 0 in reply to Nigil K
    TI__Guru**** 165886 points
    The ILIM pin voltage is proporitional to the input current. Based on your registers, the input current limit is set at 1.5A but, also per the registers, the part is reducing the input current limit per VINDPM or INDPM.
  • 0 in reply to Jeff F
    Prodigy 30 points
    Thanks Jeff for the clue. Yes I have verified the input voltage at the charger IC pin and found that it is 4.3V and I guess its cable drop.
    When I increase the DC input voltage from 5V such that I get 5V at the charger input pin, the charging current is increasing to 1.5A.
    Is there any way to compensate for this cable drop? My adapter gives just 5VDC output and it is giving 4.3V at the IC input.
    I have changed REG00 to 0x05 to reduce the input voltage threshold (to 3.88V) but still it didn't take 1.5A.
    Is there anything I need to change in order to compensate the voltage drop?