BQ24072: Charging stopped and CHG pin is blinking

UpSens Srl

Prodigy 30 points

Part Number: BQ24072

I have a BQ24072 with pulldown of:

47k on TMR

1.2k on ILIM

1.8k on ISET

CE(negated) connected to GND

TD connected to GND

EN1 to GND

EN2 to OUT

PGOOD and CHG pulled up with 10k to OUT

I put 10 devices on recharge but after some hours all of them have not charged the battery, PGOOD is low and CHG is blinking with period about 1 second.

The voltage on OUT is 4.4V constant. The voltage on IN is 5v constant. Battery voltage (rated 3.7V-1.0Ah) is 3.6V

All the devices were connected to an USB hub that supplies 5V 8.0A.

I can't find the condition happened to enter this state.

PS: it restarts individually by disconnecting and re.connecting the USB cable

over 6 years ago

0 Raheem over 6 years ago

TI__Mastermind 21590 points

Hello,
The CHG pin will blink when the safety timer expires. With a 47k ohm resistor, the safety timer is set to about 6.27 hours which should be enough to charge the battery. It seems your charge current is currently set to 0.5A. What is the load you have on OUT during charging?

0 UpSens Srl over 6 years ago in reply to Raheem

Prodigy 30 points

In this case the load current was between 100mA and 200mA.

0 Raheem over 6 years ago in reply to UpSens Srl

TI__Mastermind 21590 points

Is the charge current 500mA before the CHG pin starts blinking?

0 UpSens Srl over 6 years ago in reply to Raheem

Prodigy 30 points

I have not measured the charge current but I had 10 devices connected to the same supplier of rated 5V 8 Ampere so theoretically 0.8A for every device. Charger will then limit the current to 500mA (EN1 =low EN2= high).

0 Raheem over 6 years ago in reply to UpSens Srl

TI__Mastermind 21590 points

Please measure the charge current to ensure it is what is expected. The device will prioritize the load so if the input current is limited, the charge current will be reduced.

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BQ24072: Charging stopped and CHG pin is blinking