Bq24193 Safety Timer

Hello Teik,

In default mode, the bq24193 will have the Safety Timer set to 5hrs.  It will also follow the default charging parameters for autonomous charging.  This would mean that after terminating charging when the battery is fully charged, it would start a new charging cycle when the voltage dropped 100mV set as the default recharge threshold.

For the safety timer accuracy I could only say that since there is a +/- 14% tolerance on the digital clock, then this should apply to the 5 hrs.

Thanks,

Hi Geenja,

So in this case, the accuracy of the safety timer duration should be 5hrs +/- 42min?

This seems to be rather large if going for longer duration eg. 8hrs, which will see a tolerance of +/- 1.1hrs, which may affect the actual full charge capacity of the battery.

Hello Teik,

There doesn't seem to be anything on the Datasheet that says Safety Timer tolerance.  The only thing I could find related to timing and the clock is on page 12 in the Digital Clock and Watchdog Timer section.  In that section it gives the minimum and maximum frequencies.  I just used those values and extrapolated their meanings to the overall timing of the device.  It is not to be taken as an accurate way to determine Sleep Timer Accuracy.  

I would think though that you shouldn't expect better than +/- 5-10%, since there is no external crystal.

Thanks,

Hi Grrenja,
Further question on the safety timer setting. In " Autonomous Charging Cycle", Table 4 shows that the safety timer is 8 hours but in "Charging Safety Timer" it is 5 hours. Just like to confirm which is the correct setting. 8 hours or 5 hours for default autonomous charging?

Btw, the charging current stated in Table 4 is 2.036A. Seems a bit odd for this value. Shoudl it be 2.048A instead?

From the "Charging Safety Timer" section on page 30 of the bq24193 datasheet: 

It appears there was a type in Table 4. It will be corrected in the updated Datasheet.

Thanks!
Rachel