Share: Solution to BQ40Z80's constant hiccups

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The BQ40Z80 is a 2-cell to 7-cell battery pack manager from TI that uses Impedance Track fuel-gauging technology.

Fault phenomenon: The shutdown voltage is set at 2V, and DSG has been turned off. When I enter, I activate it again, CHG is turned on, and then connected to the charger, but CHG keeps turning on-off, on...hiccups, the battery cannot be charged normally

Solution process:

It is recommended to confirm whether it has entered PCHGC: Over-precharge current. You can try charging with the set precharge current.

I tried to reduce the current but it didn't work. It kept hiccuping. After a few minutes, it returned to normal. But I still don't know what the problem is. When connected to the host computer, the registers kept jumping around.

qwqwqw2088

Recommendation: Refer to TRM 19.2.4.5 EnabledProtectionsD and turn PCHGC disable on to verify whether it is the protection caused by pre-charge overcurrent.

These C and D items are all turned off. If there is protection, the register can report it. The strange thing is that the hiccups seem to be constantly resetting, because the date merroy is all messed up. It has been charged to the shutdown release voltage, and the SDV has been cleared. It still keeps jumping, and what's even more strange is that when the DSG is restored, it also jumps.
At this time, if you don't charge, the shutdown is released, and it keeps hiccuping until it is released after charging for a few minutes.

Suggestion: You can log some data and send a screenshot of the screen at that time to see what the test process is like.

I can't log data at all. It keeps jumping
1. I discharged the battery directly.
2. Shutdown is set to 2.5V.
3. The battery is discharged to a very low level of 1. After a few V, it has already entered shutdown.
4. The pre-charge setting uses the main CHG tube PCHG comment
5. Activate the circuit and connect the charger, and it starts jumping.
6. If you charge the battery directly, the chip does not flow current. When the battery voltage is at the shutdown value, it is normal

:
as long as it is activated, the chip does not work properly after the charging current passes. The charging tube is turned on-off, on, until it is charged for a few minutes.

qwqwqw2088

Finally found the problem, if LEDCHG is turned on, enters shutdown, then activated and charged, it will become a crazy state.

It took me a few days to find the problem.

And this is obviously a chip bug, there is no basis for it, it is just my guess.

See that this LED light is flashing normally and functions normally.

I turned it off, entered shutdown, and tried charging it, and it worked fine.

长城守护者

Thank you for sharing this bug with everyone. I have also encountered a similar problem. I have another question for you. If the CHGLED is turned off, the LED will not light up when charging. I think it is unreasonable that the LED does not light up when charging. How do you deal with this problem?

freebsder

Speaking of experience, more articles like this would be great.