BQ24040 : Battery output is 2V and not charging

Sivasubramani Kittusamy

Other Parts Discussed in Thread: BQ24040, CC2640

Hi,

We designed BQ24040 charging circuit as per datasheet schematic. TS pin is connected to CC2640 GPIO pin, but is left un-configured (floating).

We notice that BQ24040 charging output is only 2V, and also battery is not getting charged. The same circuit works fine on some samples.

We tried setting ISET2 through GPIO to Low, High & Floating, but no change in the behaviour. What might be the problem?

How to validate that IC is functional or not?

Thanks,

Siva

over 9 years ago

0 Jing Zou over 9 years ago

TI__Mastermind 20570 points

When the OUT is measured 2V, is the the battery attached? Also , is any load connected at OUT? What is the voltage on TS pin?

0 Puneet Wadhawan over 9 years ago in reply to Jing Zou

Intellectual 535 points

Yeah, the battery is connected while measuring the voltage. And the load circuit is also connected. Fortunatly since the following circuit works on 2.0V the whole of the follwing circuit is working fine. The voltage on the TS pin is 1.9XX V. This also does aligns with the understanding.

0 Jing Zou over 9 years ago in reply to Puneet Wadhawan

TI__Mastermind 20570 points

Can you measure the output voltage with the load disconnected and with the battery removed. What is the voltage of the battery when the issue occurs? Please send the screen capture on the issue with VIN, VBAT, IBAT.

0 Sivasubramani Kittusamy over 9 years ago in reply to Jing Zou

Intellectual 260 points

BQ voltage output is 2.03V with load and battery disconnected. We connected drained battery with open voltage of 30mV, the charging current is very less (~60uA).

Sorry, we didnt understand what you meant by screen capture.

0 Sivasubramani Kittusamy over 9 years ago in reply to Sivasubramani Kittusamy

Intellectual 260 points

During charging mode, we notice ~500uA current in BQ input terminal (5V). Also we notice that LED connected to PG pin is blinking, what could be the reason?

However if we enable to Load (~1.5ma), BQ is able to deliver enough power (2V - 1.5ma) and Load circuit works fine.

0 Puneet Wadhawan over 9 years ago in reply to Sivasubramani Kittusamy

Intellectual 535 points

Hi Jing,

Do you have any advice on how to root cause the problem. This device have been working for a while and then it went into this stage due to some reason. Is there a simple way to find out if the chip is functional or not?

Regards

Puneet

Power management

Power management forum

BQ24040 : Battery output is 2V and not charging