BQ24075: Not Charging the battery

Renan KASMI

Part Number: BQ24075
Other Parts Discussed in Thread: BQ27441-G1

Hello everyone,

I have trouble when I want to charge a battery thanks to the BQ24075.

When the battery is connected, it well powers the circuit. It also works well when the USB is plugged but it doesn't charge the battery.

I made several tests at different level of battery charge (20%, 50%, 70%...). I also try to change the value of the resistances, but nothing change: the battery is not charging.

I am using a BQ24075RGTT for the battery management (U7 on the schematic) and a bq27441-g1 for the gauge (U4 on the schematic).

The battery is a Varta 1/LPP 443441 S PCM W.

I am using a USB charger (5v @ 1A).

Does anyone have an idea of what it could come from?

Thank you for your help.

Renan

over 8 years ago

0 Jing Zou over 8 years ago

TI__Mastermind 20570 points

Can you take scope capture on BAT pin and /CHG pin? Please try to connect the battery directly to the charger bypassing the gauge.
Also what is the voltage of the battery?

0 Renan KASMI over 8 years ago in reply to Jing Zou

Prodigy 30 points

Thank you Jing You for your reply.

I connected the battery directly on the BQ24075 bypassing the gauge.

I have attached the scope of the BAT Pin (Vbat), the /CHG pin and the IN pin (Vin):

Vin = 5,01V
Vbat = 3,98V

I added a 10kOhm pull up resistor on the /CHG pin because nothing happens on this pin if it is not connected to a pull up resistor.

However the battery is still not charging.

Do you know what is going on?

Thank you,

Renan

0 Jing Zou over 8 years ago in reply to Renan KASMI

TI__Mastermind 20570 points

/CHG goes low indicates it is charging or charging suspended by thermal loop. What is the voltage on TS pin?

0 Renan KASMI over 8 years ago in reply to Jing Zou

Prodigy 30 points

The voltage on TS Pin is 0V (GND)
We do not use an External Thermistor. So as mentioned in the datasheet, we have a 10kOhm between TS Pin and the GND.
Thank you,
Renan

0 Kerry Song over 8 years ago in reply to Renan KASMI

TI__Intellectual 1980 points

Hello

TS pin voltage 0V is abnormal, that will suspend the charge process. please refer to p25-26 in the datasheet. There is INTC 75uA at TS pin ,if you connect 10K, the voltage should be 750mV. So please check the connection at TS pin, or replace it with a new IC to test.

Regards.

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BQ24075: Not Charging the battery