DESCRIPTION

The DS1742 is a full function, year 2000-compliant (Y2KC), real-time clock/calendar (RTC) and 2k x 8 non-volatile static RAM. User access to all registers within the DS1742 is accomplished with a bytewide interface as shown in Figure 1. The Real Time Clock (RTC) information and control bits reside in the eight uppermost RAM locations. The RTC registers contain century, year, month, date, day, hours, minutes, and seconds data in 24-hour BCD format. Corrections for the day of the month and leap year are made automatically.

FEATURES

■ Integrated NV SRAM, real time clock, crystal, power-fail control circuit and lithium energy source

■ Clock registers are accessed identical to the static RAM. These registers are resident in the eight top RAM locations

■ Century byte register

■ Totally nonvolatile with over 10 years of operation in the absence of power

■ BCD coded century, year, month, date, day, hours, minutes, and seconds with automatic leap year compensation valid up to the year 2100

■ Battery voltage level indicator flag

■ Power-fail write protection allows for ±10 VCC power supply tolerance

■ Lithium energy source is electrically disconnected to retain freshness until power is applied for the first time

■ Standard JEDEC bytewide 2k x 8 static RAM pinout

■ Quartz accuracy ±1 minute a month @ 25°C, factory calibrated