STC3115 Datasheet, PDF (17/31 Pages) STMicroelectronics – Gas gauge IC with alarm output for handheld applications

STC3115
Functional description
6.4
Power-up and battery swap detection
When the STC3115 is powered up at first battery insertion, an automatic battery voltage
measurement cycle is made immediately after startup and debounce delay.
This feature enables the system controller to get the SOC of a newly inserted battery based
on the OCV measured just before the system actually starts.
Figure 8. Timing diagram at power-up
A battery swap is detected when the battery voltage drops below the undervoltage lockout
(UVLO) for more than 1 s. The STC3115 restarts when the voltage goes back above UVLO,
in the same way as for a power-up sequence.
Such filtering provides robust battery swap detection and prevents restarting in case of short
voltage drops. This feature protects the application against high surge currents at low
temperatures.
Figure 9. Restart in case of battery swap
VCC
<1s
>1s
UVLO
POR
Short UVLO
event < 1s
No restart,
No operation
interuption
Long battery disconnection
events > 1s
STC3115 restarts
Example: When BATD/CD is high (voltage above the 1.61 V threshold) for more than 1 s, a
battery swap is detected. The STC3115 restarts when the BATD/CD level returns below the
threshold, in the same way as for a power-up sequence.
Using the 1-s filter prevents false battery swap detection if short contact bouncing occurs at
the battery terminals due to mechanical vibrations or shocks.
DocID023755 Rev 4
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