RV-8523 Datasheet, PDF (26/57 Pages) MICORO CRYSTAL SWITZERLAND – Real Time Clock

Micro Crystal
Real Time Clock / Calendar Module
RV-8523
9.2.3.BATTERY LOW DETECTION
The RV-8523 has a battery low detection circuit, which monitors the status of the battery V_BAT.
Generation of interrupts from the battery low detection is controlled via bit BLIE (register Control 3). If BLIE is
enabled, the INT_1 follows the status of bit BLF (register Control 3).
When V_BAT drops below the threshold value V_th(bat)low (typically 2.5 V), the BLF flag (register Control 3) is set to
indicate that the battery is low and that it must be replaced. Monitoring of the battery voltage also occurs during
battery operation.
An unreliable battery does not ensure data integrity during periods of backup battery operation.
When V_BAT drops below the threshold value V_th(bat)low, the following sequence occurs:
1. The battery low flag BLF is set logic 1
2. An interrupt is generated if the control bit BLIE (register Control 3) is enabled. The interrupt remains active
until the battery is replaced (BLF set logic 0) or when bit BLIE is disabled (BLIE set logic 0)
3. The flag BLF (register Control 3) remains logic 1 until the battery is replaced. BLF cannot be cleared using
the interface. It is cleared automatically by the battery low detection circuit when the battery is replaced
Battery low detection behavior with bit BLIE set logic 1 (enabled):
26/57