DESCRIPTION
The DS1689/DS1693 is a real time clock (RTC) designed as a successor to the industry standard DS1285, DS1385, DS1485, and DS1585 PC real time clocks. This device provides the industry standard DS1285 clock function with the new feature of either +3.0- or +5.0 volt operation and automatic backup and write protection to an external SRAM. The DS1689 also incorporates a number of enhanced features including a silicon serial number, power-on/off control circuitry, and 114 bytes of user NVSRAM, power-on elapsed timer, and power cycle counter.

FEATURES
Incorporates industry standard DS1287 PC clock plus enhanced features:
■ +3- or +5V operation
■ 64-bit silicon serial number
■ 64-bit customer specific ROM or additional serial number available
■ Power control circuitry supports system power-on from date/time alarm or key closure
■ Automatic battery backup and write protection to external SRAM
■ Crystal select bit allows RTC to operate with 6 pF or 12.5 pF crystal
■ 114 bytes user NV RAM
■ Auxiliary battery input
■ RAM clear input
■ Century register
■ 32 kHz output for power management
■ 32-bit VCC powered elapsed time counter
■ 32-bit VBAT powered elapsed time counter
■ 16-bit power cycle counter
■ Compatible with existing BIOS for original DS1287 functions
■ Available as IC (DS1689) or standalone module with embedded battery and crystal (DS1693)
■ IC is available in industrial temperature version
■ Timekeeping algorithm includes leap year compensation valid up to 2100