DESCRIPTION

The DS17485/DS17487 are real-time clocks (RTC) designed as successors to the industry standard DS1285, DS1385, DS1485, DS1585, and DS1685 PC real-time clocks. These devices provide the industry standard DS1285 clock function with either +3V or +5V operation. The DS17485 also incorporates a number of enhanced features including a silicon serial number, power-on/off control circuitry, 114 bytes of user NV SRAM plus 4kB of additional NV RAM, and 32.768kHz output for sustaining power management activities.

FEATURES

Incorporates industry standard DS1287 PC clock plus enhanced features:

Y2K compliant

■ +3V or +5V operation

■ SMI recovery stack

■ 64-bit silicon serial number

■ Power-control circuitry supports system power-on from date/time alarm or key closure

■ 32kHz output on power-up

■ Crystal select bit allows RTC to operate with 6pF or 12.5pF crystal

■ 114 bytes user NV RAM

■ Auxiliary battery input

■ 4kB additional NV RAM

■ RAM clear input

■ Century register

■ Date alarm register

■ Compatible with existing BIOS for original DS1287 functions

■ Available as chip (DS17485) or standalone module with embedded battery and crystal (DS17487)

■ Timekeeping algorithm includes leap-year compensation valid up to 2100

■ Underwriters Laboratory (UL) recognized