BQ24092: Safety 10h timer extension

Hello,

The fast-charge timer is fixed at 10 hours and can be increased real time by going into thermal regulation, IN-DPM or if in USB current limit. The timer clock slows by a factor of 2, resulting in a clock than counts half as fast when in these modes

Best regards,

Nick

Hi Nick,

Thank you for your quick reply.

I found this sentence in the datasheet but I do not understand what happens in this cold environment case exactly.

Twice time under this case is correct?

Hi,

Let me check on this case.

Thanks,

Nick

Hi,

Is there any datalog you can provide or waveforms showing the 20 hours? As Nick mention, this can occur either due to INDPM or USB current limit. 

What is the TS pin voltage in this case?

Best Regards,

Anthony Pham

Unfortunately I did not have any datalog for it, just counted the charge duration.

In my case I do not use USB and input voltage is above 4.5V, so I do not think it causes INDPM.

And test condition is under 5deg condition. So the TS pin voltage might be about 22kohm, I think.

Hello,

We are doing some testing on this you can expect a response within a few days.

Thanks,

Nick

Hello,

The timer does not extend solely from being in the 0-10C region. We ran a multiple tests overnight to confirm this. I would need to look at some logs to see if anything else is going on here (input voltage, TS voltage would be good.)

Thanks

Nick

Thank you for your confirmation.

We used DC power supply for input voltage at this cold condition. So it would be good.

If TS connection with battery would be unstable, does it happen?

It means that 10h timer is reset  frequently when TS connection repeated connect and disconnect condition and eventually 10h timer is extended.

Also one more question,

If TS signal does not connect, does the charge behavior goes on until the charge current reach the termination current? 

Hello,

The 10 hr timer is reset by cycling input power or going into/out of TTDM (floating TS pin). So yes, if the TS pin is unstable you could have reset the timer. 

When the TS pin is floating this is TTDM and termination/timers are disabled, device will taper down to 0mA.

Best regards,

Nick

Hi Nick,

Thank you for your quick reply.

Understood.

One more question, if the charge current decreases less than ISET current in CC mode(i.e. ISET current is 60mA but the actual charge current is 40mA by power supply performance...etc), is the 10h timer extended?

Hello,

When the adapter cannot support the programmed ISET current and you are seeing a lower charging current this the IN-DPM feature working. The timer is extended 2x in this mode, yes.

Best regards,

Nick

Hi Nick,

Understood.

I would like to confirm one thing again.

When the device is in the cold condition like 5deg, the actual charge current is not set the programmed ISET current (actually the half of the programmed one.) In this case is the timer extended 2x too?

The safety timer is not extended from going into the half charge region.

BR,

Nick