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DS12885, DS12887, DS12887A, DS12C887, DS12C887A

Real-Time Clocks

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Status Explanations for product status codes

Part Number Status
DS12885 Active: In Production. See Ordering Information for details.
DS12887 Active: In Production. See Ordering Information for details.
DS12887A Active: In Production. See Ordering Information for details.
DS12C887 Active: In Production. See Ordering Information for details.
DS12C887A Active: In Production. See Ordering Information for details.

Description

The DS12885, DS12887, and DS12C887 real-time clocks (RTCs) are designed to be direct replacements for the DS1285 and DS1287. The devices provide a real-time clock/calendar, one time-of-day alarm, three maskable interrupts with a common interrupt output, a programmable square wave, and 114 bytes of battery-backed static RAM (113 bytes in the DS12C887 and DS12C887A). The DS12887 integrates a quartz crystal and lithium energy source into a 24-pin encapsulated DIP package. The DS12C887 adds a century byte at address 32h. For all devices, the date at the end of the month is automatically adjusted for months with fewer than 31 days, including correction for leap years. The devices also operate in either 24-hour or 12-hour format with an AM/PM indicator. A precision temperature-compensated circuit monitors the status of VCC. If a primary power failure is detected, the device automatically switches to a backup supply. A lithium coin-cell battery can be connected to the VBAT input pin on the DS12885 to maintain time and date operation when primary power is absent. The device is accessed through a multiplexed byte-wide interface, which supports both Intel and Motorola modes.

Data Sheet

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This product contains lithium-metal batteries. See applicable regulations for transport requirements for batteries in equipment.

Key Features

  • Drop-In Replacement for IBM AT Computer Clock/Calendar
  • RTC Counts Seconds, Minutes, Hours, Day, Date, Month, and Year with Leap Year Compensation Through 2099
  • Binary or BCD Time Representation
  • 12-Hour or 24-Hour Clock with AM and PM in 12-Hour Mode
  • Daylight Saving Time Option
  • Selectable Intel or Motorola Bus Timing
  • Interfaced with Software as 128 RAM Locations
  • 14 Bytes of Clock and Control Registers
  • 114 Bytes of General-Purpose, Battery-Backed RAM (113 Bytes in the DS12C887 and DS12C887A)
  • RAM Clear Function (DS12885, DS12887A, and DS12C887A)
  • Interrupt Output with Three Independently Maskable Interrupt Flags
  • Time-of-Day Alarm Once Per Second to Once Per Day
  • Periodic Rates from 122µs to 500ms
  • End-of-Clock Update Cycle Flag
  • Programmable Square-Wave Output
  • Automatic Power-Fail Detect and Switch Circuitry
  • Optional 28-Pin PLCC Surface Mount Package or 32-Pin TQFP (DS12885)
  • Optional Encapsulated DIP (EDIP) Package with Integrated Crystal and Battery (DS12887, DS12887A, DS12C887, DS12C887A)
  • Optional Industrial Temperature Range Available
  • Underwriters Laboratories (UL) Recognized
 

Applications/Uses

  • Embedded Systems
  • Network Hubs, Bridges, and Routers
  • Security Systems
  • Utility Meters
   

Key Specifications:

Timekeeping & Real-Time Clocks
Part Number Interface VSUPPLY
(V)
Time Keeping Current
(nA)
CL
(pF)
Memory Type Memory Size
(Bytes)
Time of Day Alarms Budgetary
Price
typ See Notes
DS12885  Multiplexed 5 225 6 NV SRAM 114 1 $2.97 @1k
DS12887  - - 114 $4.70 @1k
DS12887A  - - 114 $4.70 @1k
DS12C887  - - 113 $4.70 @1k
DS12C887A  - - 113 $4.76 @1k
See All Timekeeping & Real-Time Clocks (90)

Pricing Notes:

This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.



Diagram

DS12885, DS12887, DS12887A, DS12C887, DS12C887A: Typical Operating Circuit
Typical Operating Circuit

More Information

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Information Index

Document Ref.: 19-5213 Rev 4; 2010-05-06
This page last modified: 2010-05-06