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BQ24104: Charger IC not charging, output voltage is the same as the input voltage

Deniel Go
Intellectual 355 points
Part Number: BQ24104
Other Parts Discussed in Thread: BQ24103,

Hello,

Our team is currently debugging our BQ24104 charger IC board. We are comparing our results with the data we got from the BQ24103 EVB. Here are our observations

A. With the 2S4P  battery connected, when we connected the 15V Power Adapter in the input.

1. There is little to no current draw. It is around 30mA from the power supply. 

2. The battery voltage is slightly discharged to around 8V.

3. When we plug the battery and 15V power adapter to the BQ24103 EVB, we are seeing the expected current draw of 1.5A.

4. The STAT1 and STAT2 LEDs are OFF

5. We measured that the PG pin is pulled to ground via measuring the resistance between the pin and the ground. It was open load when the 15V adapter not connected and it was near 0 ohms when the 15V was connected to the input.

6. Charge Enable pin is tied to the GND. RC7 was changed from 10k to 0 ohms. 

7. We are measuring the correct voltages in the VTSB and TS pin. It is similar to the VTSB and TS pin voltages on the EVB. (VTSB=3.2V and TS=2.216V)

8. We are measuring around 0V in the ISET1 and ISET2 Pins

B. With the 2S4P battery removed and the 15V Power Adapter connected

1. In the EVB board, we probed the the BAT pin of the charger and we observing a square wave that goes from 0V to around 8.4V. We know this is expected because of the battery detection process as noted in Section 8.3.16 of the BQ241xx datasheet. 

2. In our Charger IC board, we are measuring a constant 14.46V in the BAT pin instead of the battery detection voltage.

We would like to know how should we go about debugging this issue. It was working up until recently. How would we know if the charger IC is damaged since we are still able to measure the expected voltages on some pins (TS, VTSB, PG).

The setup for testing our charger IC board before it failed is as follows

Input Voltage: 12V

Battery: 2S4P

Fast Charge Setting: 2A

Current Schematic:

Thanks,

Deniel

  • 0
    TI__Mastermind 33655 points

    Dear Deniel,

    My schematic review is as follows:

    1. We require a 0.1 uF capacitor from VCC to VSS as close to VCC as possible.

    2. Safety timer and termination are both disabled because TTC is pulled low.

    3. 2 cell because CELLS pulled up to VCC.

    4. 200 mA precharge and termination current.

    5. Fast charge current is either 1 A or 2 A.

    As for your description, can you please verify that the battery is plugged in? For the BQ24104 if STAT1 and STAT2 are off the battery is absent. Also, how is your TS voltage 2.216 V? Because of the equal voltage divider it should be VTSB = 3.2 V divided by 2 or 1.6 V.

    Something is not right if you are measuring a constant 14.46 V instead of battery detection. Have you tried replacing the IC?

    Thanks,

    Mike Emanuel

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