RV-3049 datasheet(23/65 Pages) MICROCRYSTAL

23 / 65 page

Micro Crystal

DTCXO Temperature Compensated Real Time Clock / Calendar Module

RV-3049

23/65

Example Power Up sequence, Low Voltage detection and Backup Supply switchover

Power Up Reset is executed; registers are loaded with Reset Values. PON flag is set at Power up

indicating that time / date information likely are corrupted.

Low voltage detection flags VLOW1 and VLOW2 are automatically cleared.

PON Flag needs to be cleared by software writing “0”.

Trickle charge circuitry for backup battery can be enabled by software.

Switchover to the backup supply voltage when VDD drops below VDD < (VBAT – 20mV).

Low voltage detection sets VLOW1 Flag when supply voltage drops VLOW1 threshold.

Low voltage detection sets VLOW2 Flag when supply voltage drops VLOW2 threshold.

Switchback from backup supply voltage to main supply voltage when VDD rise above VDD > (VBAT + 20mV).

VLOW1 and VLOW2 Flags need to be cleared by software writing “0”.

4.1.2.SUPPLY VOLTAGE OPERATING RANGE AND LOW VOLTAGE DETECTION

The RV-3049 has built-in low supply voltage detection which periodically monitors supply voltage levels vs. VLOW1

and VLOW2 thresholds.

If low supply voltage is detected, the corresponding flags VLOW1 and VLOW2 are set = “1”. Device functions critical to

low supply voltage are disabled.

During power up, the Low Voltage Detection is monitoring the supply voltage at an accelerated scan rate. If power

supply voltage exceed VLOW2 threshold, the flags VLOW1 and VLOW2 are cleared and the scan rate for the low voltage

detection is set to 1 second.

RV-3049 Datasheet(PDF) 23 Page - MICORO CRYSTAL SWITZERLAND