BQ24090: BQ24090 Charging current is small.

wei xiong

Part Number: BQ24090

hi Engineer:

My circuit diagram is shown in the figure above.

USB plug in to charge the battery.Testing 5V current is only 20mA.The battery is charging at a very slow rate.The current battery voltage is 3.8V.

ISET2 is connected to BATT through 10K resistor. The current is about 20mA.

Is this normal?Or is there any problem with my circuit?

Thanks！！！

over 6 years ago

0 Bill Johns over 6 years ago

TI__Guru 69711 points

Hello
Connections and resistor / capacitor values look OK. ISET pin should be setting the output current to about 1A.
Somethings to check:
1.) Input voltage at the IC to make sure voltage is not low.
2.) Output voltage at IC with a scope.
3.) Device is not overheating ( thermal rise will limit output current)
4.) Voltage at ISET pin, this is a proxy for output current.

0 wei xiong over 6 years ago in reply to Bill Johns

Prodigy 50 points

Thank you for your reply！

I measured the input voltage is 5V, the output voltage BATT is 3.8V, IC is not heated, I will measure the ISET voltage later.

0 wei xiong over 6 years ago in reply to Bill Johns

Prodigy 50 points

I test the ISET pin voltage to 1V。

The charging current is 200mA.

0 Bill Johns over 6 years ago in reply to wei xiong

TI__Guru 69711 points

Sorry for the late reply.
With ISET voltage at 1V and resistor at 540 ohms the output current should be between 700mA to 600mA. But you are seeing 200mA. How are you measuring the current to battery?

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BQ24090: BQ24090 Charging current is small.