Part Number: BQ24075
I have designed a Li-Ion charger with the BQ24075 based on the schematic below.
Problem: When I connect a voltage at IN (5V, current limit >2A), the LED at the CHG pin is illuminated, but the battery is not charged (I measured the battery current)
- Without anything applied at the IN pin, the battery voltage appears at the OUT pin, so this seems to work as expected
- I connected a 10k NTC at the TS pin
- The only difference I can see compared to the reference schematic is that EN2 and the charge LED are connected to IN instead of OUT. As those are digital terminals, I don't expect problems from this
Any idea what could be the problem?
Can you measure the voltage on TS? is CE low? Is there any load on VOUT?
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In reply to Raheem:
Thanks for your reply!
- Voltage on the TS pin is 0V (a 10k NTC is connected)
- CE is low (connected to GND)
- Load on VOUT: Same behaviour with load (20mA) and without load.
In reply to Lukas Bereuter:
Voltage on TS pin should be between 300mV and 2.1V. Can you try replacing the IC.
Is the 10k resistor properly connected to the NTC pin
- I replaced the IC several times, still no voltage at the TS pin. It is the same problem on all of the 4 PCBs. But: the LED at the CHG pin is illuminated. How can that be when it's not charging?
- Also the 10k resistor is properly connected to the TS pin
Can you do a continuity test on TS pin to make sure it is not shorted to ground when the resistor isn't present?
The device will never charge with the TS pin at 0V
I measured the current coming out of the TS pin: there is no current flow out of the TS pin.
I also measured the resistance between TS and GND. It is 10k when the NTC is placed and high impedance without NTC present.
Could this be a batch issue? As I said, it's the same problems on all 4 PCBs...
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