3 Volt/5 Volt Serialized Real-Time Clock with NV RAM Control

The DS1688/DS1691 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 +5.0V operation and automatic backup and write protection to an external SRAM. The DS1688 also incorporates a number of enhanced features including a silicon serial number, power on/off control circuitry, 114 bytes of user NV SRAM, power on elapsed timer, and power cycle counter.

* +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

* 6pF or 12.5pF crystal

* 114 bytes user NV RAM

* Auxiliary battery input

* RAM clear input

* Century register

* 32kHz 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 (DS1688) or stand-alone module with embedded battery and crystal (DS1691)

* Timekeeping algorithm includes leap year compensation valid up to 2100