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Original question:

BQ25606: Selecting charging current to either 500mA for SDP and 1A for everything else

BQ25606: Battery Charging Current Issues

Jobby
Prodigy 120 points
Part Number: BQ25606

The BQ25606 IC is connected to a micro-usb port. Both D+/D- lines are connected to the D+/D- ports on BQ25606 IC. The ICHG and ILIM current are both set to 1A. My goal is to charge the battery at 500mA when connected to SDP and at 1A  for wall adapters. However, when measuring the charging current I am only seeing approx 420mA (max) its when connected to SDP and only 530mA (max) when connected to a wall adapter. Please advise on why the charging current is not reaching 1A when connected to wall adapters. Is there additional circuitry needed to connect the D+/D- lines to the IC?

Thank You,

Jobby 

  • 0
    TI__Expert 5590 points
    420mA charge current is close to the 500mA. SDP maximum allowed current is 500mA. When you connected to wall adaptor, there are a couple of possibility that the current is less than it set:
    1. Check ILIM and ICHG resistance
    2. Cable is too long and VBUS voltage is low (VINDPM)
    3. Adaptor D+/D- is not configured correct.

    Please short D+ and D- and check BQ25606 input current.
  • 0 in reply to Hong Mao
    Prodigy 120 points

    Hong Mao said:
    420mA charge current is close to the 500mA. SDP maximum allowed current is 500mA. When you connected to wall adaptor, there are a couple of possibility that the current is less than it set:
    1. Check ILIM and ICHG resistance

    ICHG is set to 681 ohms and ILIM is set to 475ohms

    2. Cable is too long and VBUS voltage is low (VINDPM)

    The cable length is standard. However I noticed the VBUS voltage sometimes fluctuates around +/- 0.5V (from 5V to 4.5V). This causes the STAT pin to blink at 1Hz rate. Any reason for the VBUS to be changing this much? Additionally, does adding an ammeter interfere with the charging current rate?
    3. Adaptor D+/D- is not configured correct.

    Please short D+ and D- and check BQ25606input current.

    Wouldn't shorting the D+ and D- set it to DCP mode? Which will set the charging current to 2.4A?

  • 0 in reply to Jobby
    TI__Expert 5590 points

    Hi Jobby:

    2. If STAT pin is flashing, charging is abnormal. Can you remove the ammeter and check input current instead? Make sure your power supply can provide enough current.
    3. Shorting D+/D- will set the current limit at 2.4A, charge current is set by ICHG resistance. In this case, you will know if the issue is caused by D+/D- or not.
    4. If you float D+/D-, the current limit is programmed by ILIM resistor. You may try that as well.