BQ25616: Question about sch and also about possible Faults

Thales,

I cannot see your schematic. Please reattach it.

Best Regards,

Ricardo

Thales,

The BQ25616 when the battery is not present STAT is blink rapidly because the C610 is charging and discharging rapidly.

How can the device enter OTG with no battery present? I think you are unclear on the use of OTG. OTG is meant to supply an accessory connected to VBUS with power delivered on the battery. If there is no power available, then you cannot enter OTG.

Best Regards,

Ricardo

Hello ricardo thanks or the reply.
I think i was not very clear of what was happening , but when i meant otg i meant the pin. let me explain what i have in mind:
I want the b125616 to work as the booster for backup energy. My idea is to have always the battery on, at almost full charge, so that when needed the IC 
can enter boost mode and keep suplying the 5V bus. So when energy comes back online the IC exist boost mode and go back to just charging the battery . I noticed that when the IC enters boost mode and then the power comes back it needs a low step input on the  OTG pin to "reset" in a way and resume charging.
The thing is, what are the possible faults that lead to not charging the battery, in a board i mounted the stat pin keeps blinking even though i checked that there is no overvoltage, no TS fault ( i changed the values in the ts resistors to 10k in order to not have any faults due to TS )  no system over voltage and i restarted the board many times so it cant be the safety timer fault. am i missing something so that the board can charge?
thank you for your time, 
Thales

Thales,

I believe what may be occuring is that /CE is staying high. Could you capture /CE, OTG, VBUS, and /PG when you transition form buck mode to boost mode?

Best Regards,

Ricardo

Ricardo,
as you gans see in the schematics the /CE pin is pulled down with the 10k resistor R615,  is it possible for it to be staying high even with it pulled down ?

Also. you want me to capture all those signals at the same time or can it be separate? 

Best Regards,
Thales

Thales,

My mistake I confused for OTG. I am still a bit confused however. So when an adaptor is present at 5V_IN, OTG isd driven HIGH and boost mode is enabled to produce an output at VBUS_IN? This does not seem right. When an adaptor is absent, OTG is just floating and this condition is not allowed by the datasheet.

Please disregard capturing the waveforms.

Best Regards,

Ricardo

Ricardo

This is suposed to work as follows: 
the circuit is connected to an AC wall plug, a AC-DC converter on the board supplies the 5V that is labled 5V_IN and this charges a backup battery. This makes the OTG pin driven HIGH. When an error happends and the AC power is turned off , the PG pin goes LOW indicating a faulty source and the IC should  enter boost mode operation from battery. This kind of operation is possible with this IC, right?
Thank you
thales

Thales,

So when 5V_IN is 5V and power is present you want to enter boost mode and output the VBUS_IN?

Boost mode provides a regulated output on VBUS supplied by VBAT. If you are shorting the two regulated outputs, you will have issues.

Best Regards,

Ricardo

Ricardo,

In the datasheet 9.3.4 states that the boost mode only activates when VBUS is lower than VBAT + VSleep.
Shouldn't it be impossible to enter boost mode when 5V_IN is powered from an external source?

Best regards 
thales

Thales,

Your understanding is correct. That is why I am confused.

The OTG pin is pulled up to 5V_IN.

When the adaptor is present, 5V_IN is 5V, the OTG pin is 5V, and the device will try to enter boost mode but will fail.

When the adapter is absent, 5V_IN is floating, the OTG pin is floating, this is an undefined state for the OTG pin. The device will not operate correctly.

Neither situation is useful.

Best Regards,

Ricardo

Ricardo , 
if i change the source of the pull-up to the 3.X from the battery would this circuit work ?
I want it to change to the boost mode as soon as the 5v input goes down in order to keep the rest of the board working without restarting.
And i also want it to change batck to charging mode as soon as the 5v input from the AC/DC returns .

So ricardo,
After changing the driving source of the OTG pin i noticed thet the /PG is not returning to 0 , but when i force it to zero with a jumper it stays at 0. This makes the charger not be able to work  as 'standalone'. Am i missing something or this is the expected behaviour of the /PG pin ? 
thank you ,
Thales

Thales,

Show me how it is connected.

/PG is an open drain 

Ricardo,
the thing is, the /PG is not returning to open drain mode after the input is restored. I conected the /PG pin to drive OTG so that the IC enters boost mode only when Power input is missing, but when the power input is restored the /PG does not return to LOW . I think the IC is not returning to charging mode for some reason, even if the requirements for a good voltage input are met.

Thales,

Does it return to LOW, if OTG is toggled manually?

Best Regards,

Ricardo

Yes Ricardo, if OTG is toggles /PG stays at 0V and the IC goes back to charging mode
Best regards 
Thales

Thales,

Is there any signal or mechanical connection you could use instead of /PG to match an adapter plugged/absent to drive OTG appropriately?

Best Regards,

Ricardo

Ricardo,
Unfortunetly thsi cannot be an option, i chose this ic exacly because it is suposed to work standalone. Is there something i can do to make it work as described in the datasheet?
Best regards,
Thales