BQ24080: Charge Done State never show up (Status LED, STAT2 pin)

Hello

Do you have a schematic of your circuit that I can review.

Hi Bill,

There is the schematic :

Hello

The schematic looks OK.

Have you bypassed the BQ24314 and does it change the behavior?

Good idea i'll try it and come back to you. 

Thanks. 

Hi,

So i removed the BQ24314 but it did not change anything. 

I started  questioning the 5V DC/DC plugged on the VBATT power line, it is a : TPS61022RWUR, i removed it and the green LED finally worked.

Do you have an idea of why it happening? I need the DC/DC, do you have an idea of how i can have both working properly?

Thanks. 

Hi

Couple of thoughts, is the boost converter voltage dropping out of regulation during the charge cycle?  This could possible cause problems with termination.

During Termination the current will decrease to a low level.  This would be a light load on the TPS61022 and it may enter PFM mode which is high efficiency but high noise. 

How close is the TPS61022 to standard EVM? Do you have a schematic you can share?

Hi,

So i tested it and the voltage do not drop, there is a 5V ish (4.98V).

During the charging phase there is almost no load except a chip that is alive and consume 6uA

Here a picture of the DC/DC :

Sorry for the delay.

I am trying to duplicate the problem and have ordered the TPS61022.

Hi,

Thanks for the follow-up,

Your help is appreciated!

Hello

A theory we are investigating.

The TPS61022 operating in PFM mode (MODE Low) at light load will operate in a burst type of mode.  Switching burst to charge output capacitor with low current between the burst. 

BQ24080 has a long termination deglitch time of 375mS.  The current needs to be below termination for level for this time, if the current spikes above this level the deglitch timer starts over.

We are looking at the combination of the two features preventing charge complete.

Hi,

Sound logical, based on that i suppose that during the charge if we disable the TPS61022 by the Enable pin it may solve the issue?

Hi

If you could test with the BQ61022 MODE pin pulled up (PWM Mode) this would prevent the large current spikes during PFM burst mode.  Light load efficiency would be lower.  Should this work possible fix would be to pull the MODE high during charging or external power present.

Ok i'll check if it is possible on the board i have.

Thanks.