Datasheet

DocID023755 Rev 4 17/31
STC3115 Functional description
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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
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.
VCC
UVLO
Short UVLO
event < 1s
No restart,
No operation
interuption
<1s
Long battery disconnection
events > 1s
STC3115 restarts
>1s
POR