GENERAL DESCRIPTION
The DS1688/DS1691 are real-time clocks (RTCs) designed as successors to the industry standard DS1285, DS1385, DS1485, and DS1585 PC real-time clocks. These devices provide the industry standard DS1285 clock function with the new feature of either +3.0V 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.

FEATURES
Incorporates Industry Standard DS1287 PC Clock Plus Enhanced Features:
*+3V 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

DS1688S, DS1688S+, DS1691

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