BQ25306: STATUS pin level behaviour

Hi Tristan, the first think to check would be how you have set the POL pin of the charger which sets the EN pin polarity, however in your case it should be fine to leave it floating.

Second you say that the STATUS pin is pulled high to REGN, I just want to confirm that it is not tied directly to REGEN but is connected thought a resistor, or  combination of a resistor and LED.

Lastly when you say that the STATUS pin goes low-high-low, do you mean that an LED connected to the status pin goes off-on-off or does the voltage on the pin its self go low-high-low.

Any Schematics, or waveforms demonstrating this behavior would also be useful in helping debug this issue.

NORPHE_Battery_Board.pdf

Hello, here the schematic part of the charger. STATUS pin is connected to GPIO input of a MCU. 

For recap, when /EN is high, STATUS pin go high only for around 100ms an then is drived low (that's the part i don't understand. When /EN go to low, i can see a brief pike to high of the STATUS voltage.

Thanks  

Hi Tristan, what is the voltage on the battery at this point. The STAT pin state is based on these three Items. Also when you are enabling the device, by driving /EN low and seeing this spike in status voltage, is the large 10A load still connected. Also where is this load connected to, the VBUS input, or SYS output?

Hi, here some pins measurements. Load is conected to PACK+ node in my schematics. In my understanding, STATUS voltage must be high when /EN is high, and low when /EN is low, but this is not the case...

Hi Tristan, in your original post you way that you deactivate the charger when you want to power the 10A load. Is the load then being disconnected before the charger is re-enabled.

The load is not connected/disconnected mechanically, the load is composed of a heating element controled in PWM by a buck boost. So when current is injected into load (around 10A), the MCU pull up /EN signal to deactivate the charger to avoid current excess flowing from it. You can see the battery voltage fluctuations when correct is flowing into load (from 4.0V to 3.7V)

Hi Tristan, the REGN supply is only powered up when the chip is enabled, my suspicion is that when you drive the EN pin low, the REGN supply powers up while the STAT pin is still open (high impedance) this shows as the stat pin being high for a brief moment. Once charging enables, the STAT pin is driven low.

OK, i understand. So, what i see is the expected behaviour ?

Yes that is the behavior we expect to see, although I see there is no STAT pin spike when EN goes low at the end of the wave form. Are the test conditions the same at towards the end of the wave form.

Hi, no dont take into account the end of waveform, it is a wrong measurement. The good measure is the middle of waveform. So finally, can you sum up what happens on STATUS precisely when /EN goes down and up concerning my waveform?

All is clear, thanks for explanations !

Sounds good I will go ahead and close the thread