• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 62 subscribers
  • Views 651 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ24014: Battery not charging despite STAT1 being low

Daniel Truong
Intellectual 270 points
Part Number: BQ24014

Hi,

Please help me to identify the root cause of the following problem:

I'm using BQ24014 to charge my Li-Ion battery removable pack. I'm also using BQ27421 Fuel Gauge as companion to measure current and charge going in/out of the battery.

The problem is, when I apply an external power source (in this case is USB voltage ~5V) to pins IN and VCC, there is no current (0 mA as measured by the fuel gauge) flowing to the battery. The STAT1 pin did go low, indicating charging.

The voltage level at the pins are as follows:

VCC=IN=5V (connected to USB power line)

OUT=BAT=3.9V (connected to Fuel Gauge in series with the battery)

TS=2.39V (connected to a pair of resistor divider, but not connected to battery)

ISET=3.9V (pulled down with 3.3K resistor)

STAT1=0 (pulled up)

STAT2=3.3V (pulled up)

Thanks,

Daniel

  • 0
    Intellectual 270 points

    As you can see, I have no problem with the battery in discharging mode (i.e. when there is no USB external voltage indicated by P_VBUS). The battery would discharge current from J1 to U6 (Fuel Gauge), then bypassing U5 all the way to the load (indicated by TP4 in the upper right corner). In this mode, both STAT1 and STAT2 are high as expected. Both battery and output load voltages are 4.13V. Current measured by the Fuel gauge varies from -30mA to -140mA depending on load conditions (note: there is an error on the schematics associated with R32 placed across pins BIN & V180, rework was done to correct it but it's irrelevant with this issue).

    When I inserted USB cable to the board, the STAT1 pin showed LOW (indicates charging). However, fuel gauge showed 0 mA current and SOC never changed. The rest of the board still works because the load gets the voltage from USB power (via D2). The only issue is the battery can't be charged because the BQ24014 won't output current.

    On a side note, I changed R2 to 22K and disconnected from J1 to fix the voltage at TS pin at 2.39V as mentioned above (falls between threshold 61% and 30% of VCC=5V). If I kept the original design as in schematics, the TS voltage level was too low (1.31V) and the STAT1 pin of the BQ24014 would not even go low.

    With this change, the STAT1 showed LOW except that the chip wouldn't supply current.

    Can you please help?

    Thanks in advance.