RV-8523 Datasheet, PDF (8/57 Pages) MICORO CRYSTAL SWITZERLAND – Real Time Clock

Micro Crystal
Real Time Clock / Calendar Module
RV-8523
6. FUNCTIONAL DESCRIPTION
The RV-8523 RTC module combines a RTC IC with on chip oscillator together with a 32.768 kHz quartz crystal in a
miniature ceramic package.
The RV-8523 contains:
• 20 8-bit registers with an auto-incrementing address register
• A frequency divider, which provides the source clock for the real time clock (RTC)
• A programmable clock output
• A 1 Mbit/s I²C bus interface
• An offset register, which allows fine-tuning of the clock
All 20 registers are designed as addressable 8-bit registers although not all bits are implemented:
• The first three registers (memory address 00h, 01h, and 02h) are used as control and status registers
• The addresses 03h through 09h are used as counters for the clock function (seconds up to years)
• Addresses 0Ah through 0Dh define the alarm condition
• Address 0Eh defines the offset calibration
• Address 0Fh defines the clock-out mode and the addresses 10h and 12h the timers mode
• Addresses 11h and 13h are used for the timers
The registers Seconds, Minutes, Hours, Days, Weekdays, Months, and Years are all coded in Binary Coded
Decimal (BCD) format. Other registers are either bit-wise or standard binary. When one of the RTC registers is
read, the contents of all counters are frozen. Therefore, faulty reading of the clock and calendar during a carry
condition is prevented.
The RV-8523 has a battery backup input pin and battery switch-over circuit, which monitors the main power supply
and automatically switches to the backup battery when a power failure condition is detected. Accurate timekeeping
is maintained even when the main power supply is interrupted.
A battery low detection circuit monitors the status of the battery. When the battery voltage goes below a certain
threshold value, a flag is set to indicate that the battery must be replaced soon. This ensures the integrity of the
data during periods of battery backup.
7. DEVICE PROTECTION DIAGRAM
8/57