BQ2031 LED2 blinks in MODE 1

You would need to know what is happening with the pack being charged when this occurs to know for sure.

It could be that the charger is switching between two states which makes it look like the LED is flashing when in reality it is merely going from high to low and back.

You could also confirm that you are looking at LED2 and not 1 or 3 and that DSEL is properly connected to register a logic low at boot up per the datasheet.

You would need to know what is happening with the pack being charged when this occurs to know for sure.

This states keeps with or without the pack conected to the board.

It could be that the charger is switching between two states which makes it look like the LED is flashing when in reality it is merely going from high to low and back.

I believe it was my fault not mention that this board was already working right and this status  started to be reported  after our stress tests in our HALT chamber. (temperature and vibration tests)

You could also confirm that you are looking at LED2 and not 1 or 3 and that DSEL is properly connected to register a logic low at boot up per the datasheet.

How I mentioned this circuit was already working. This status started to be reported after our stress tests. Btw, I had already confirmed that all the other componentes of the BQ2031 circuit are with their integrity according with other board working correctly

Ah yes, this is very important information that this only occurred after stress testing.  Did other systems pass the testing without issues?

It would be good to see the Vcc, BAT, COM, and LED2 pins when that LED is flashing.

Here it is.

In a good board, working perfectly fine:

VCC: 4,967V

BAT: 2,382V

COM: 0V

LED2: 0V

In a board with the same material list mounted. Using the same battery. After our stress tests:

VCC: 4,957V

BAT: 2,160V

COM: 0V

LED2: A square wave with 4,95V max.

Another point is, after some few minutes the LED2 stop to flash and keep alive all the time.

And yes. All other parts and circuits of our board "survived" to our stress tests.

Thanks for providing this.  What do LED1 and LED3 look like on a good board and on the one that failed?

Also, what is the frequency and duty cycle of the square wave on LED2?  I assume it goes from 4.95V to 0V?

Finally, do you have a schematic that you can share?

I sent you a friend request.  Once you accept it, you should be able to start a conversation with me where you can upload your schematic.  Conversations are private.

Might there be a few typos in your response above?  You mention LED2, but might it be LED3 that you mean?  I would like to know what LED1 and LED3 are doing.

Sorry, I did a mistake in fact:

LED1 are flashing while Pre-charge qualification . Also have a square wave on the BQ2031 pin. LED3 are low and also have 0V on their pin.

On the board that failed LED1 and LED3 are low all the time. Whit or without the battery

Thanks for providing your schematic.  It appears that the LEDs are driven fine.

Just to summarize what has been said so far, after stress testing one PCB keeps LED1 and LED3 low (off) and LED2 blinks.  Is this a correct summary?  Does this state change after some time?

I would recommend swapping the IC on the failing board with a known good IC from another board.  If the same LED2 flashing case follows the IC, then this gives some information.

Also, could your testing have violated any of the absolute maximum ratings of the device?  I am thinking of temperature specifically.

Hi Chris,

The Summarizing are correct. I Believe I mentioned before, but in the in the fail board after some minutes blinking LED2 stops blinking and stays on. Again, with or without a battery connected.

I Just Swapped the IC and it started to work fine.

Our stress tests was driven in 0C to 60°C. And the failure happened in 60°C in vibration mode. 

btw, can answer here the specification of the marking code on the top of the IC? For example: "they need to have the TI logo and XXX YYY ZZZ character and each character means:" We are trying to identify the lotes of manufactoring.

On the bq2031's product page in the 'sample and buy' section, there is a link to view the top side marking information.

Since a new IC made that board work properly again, it seems like you have damaged the IC.  Since your temperature is relatively low, it is likely the vibration testing caused some damage.  I'm not sure what else I can do for you except to say that you can work with your distributor to have them return the failed device to TI where we can run testing on it to confirm that the device is in fact damaged.

I believe it ends the conversation for now.

I'll contact our suplier to arrange all with them. 

Thanks for all you support