DETAILED DESCRIPTION The DS1685/DS1687 are real-time clocks (RTC) designed as successors to the industry-standard DS1285, DS1385, DS1485, and DS1585 PC RTCs. These devices provide the industry-standard DS1285 clock function with either +3.0V or +5.0V operation. The DS1685 also incorporates a number of enhanced features including a silicon serial number, power-on/off control circuitry, 242 bytes of user NV SRAM, and 32.768kHz output for sustaining power management activities. FEATURES ■ Incorporates Industry-Standard DS1287 PC Clock plus Enhanced Features Such as Y2K Compliant ■ +3V or +5V Operation ■ 64-Bit Silicon Serial Number ■ Power-Control Circuitry Supports System Power-On from Date/Time Alarm or Key Closure ■ 32kHz Output for Power Management ■ Crystal-Select Bit Allows RTC to Operate with 6pF or 12.5pF Crystal ■ SMI Recovery Stack ■ 242 Bytes Battery-Backed NV RAM ■ Auxiliary Battery Input ■ RAM Clear Input ■ Century Register ■ Date Alarm Register ■ Compatible with Existing BIOS for Original DS1287 Functions ■ Available as Chip (DS1685) or Stand-Alone Encapsulated DIP (EDIP) with Embedded Battery and Crystal (DS1687) ■ Timekeeping Algorithm Includes Leap-Year Compensation Valid Through 2099 ■ Underwriters Laboratory (UL) Recognized APPLICATIONS Embedded Systems Utility Meters Security Systems Network Hubs, Bridges, and Routers
The DS1687-3+ is a real time clock with +3V operation in 24 pin EDIP package. It is designed as successors to the industry standard DS1285, DS1385, DS1485 and DS1585 PC RTCs. The device provides industry standard DS1285 clock function with +3V operation. The DS1687 incorporates a DS1685 chip, 32.768KHz crystal and lithium battery in a complete, self contained timekeeping EDIP package. The entire unit is fully tested such that a minimum of 10 years of timekeeping and data retention in the absence of VCC is provided. Power control circuitry allows the system to be powered on by an external stimulus such as a keyboard or by a time and date (wake-up) alarm. The PWR output pin can be triggered by one or either of these events and can be used to turn on an external power supply. It is used in embedded systems, utility meters, network hubs, bridges and routers. The crystal select bit allows RTC to operate with 6pF or 12.5pF crystal.
The DS1687-3IND+ is a real time clock with +3V operation in 24 pin EDIP package. It is designed as successors to the industry standard DS1285, DS1385, DS1485 and DS1585 PC RTCs. The device provides industry standard DS1285 clock function with +3V operation. The DS1687 incorporates a DS1685 chip, 32.768KHz crystal and lithium battery in a complete, self contained timekeeping EDIP package. The entire unit is fully tested such that a minimum of 10 years of timekeeping and data retention in the absence of VCC is provided. Power control circuitry allows the system to be powered on by an external stimulus such as a keyboard or by a time and date (wake-up) alarm. The PWR output pin can be triggered by one or either of these events and can be used to turn on an external power supply. It is used in embedded systems, utility meters, network hubs, bridges and routers. The crystal select bit allows RTC to operate with 6pF or 12.5pF crystal.