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Maxim > Products > [Real-Time Clocks] 
DS12885, DS12887, DS12887A, DS12C887, DS12C887A
Real-Time Clock


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Status
Part Number Status
DS12885 Active: In Production. But some versions of the family are No Longer Available. See Ordering Information.
DS12887 Active: In Production.
DS12887A Active: In Production.
DS12C887 Active: In Production.
DS12C887A Active: In Production.

Data Sheet
FULL DATA SHEET (PDF, 240kB)
Download this datasheet in PDF formatDownload   Send this datasheet to any email addressE-Mail

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.

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

Key Features   Applications/Uses
  • 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

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

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

    Application Notes
  		• Application Note 58: Crystal Considerations with Dallas Real-Time Clocks (RTCs) - DS12885
  		• Application Note 503: Replacing the DS1287/DS12887 Real-Time Clock in a Personal Computer - DS12C887A, DS12887, DS12887A, DS12C887
  		• Application Note 504: Design Considerations for Dallas Semiconductor Real-Time Clocks - DS12885, DS12887
  		• Application Note 505: Lithium Coin-Cell Batteries: Predicting an Application Lifetime - DS12885
  		• Application Note 516: Using Multiplexed Bus Clocks with a Microcontroller - DS12885, DS12887, DS12C887
  		• Application Note 521: Replacement for the MC146818 - DS12C887A, DS12885, DS12887, DS12887A, DS12C887
  		• Application Note 522: Replacement for the MC146818A - DS12C887A, DS12885, DS12887, DS12887A, DS12C887
  		• Application Note 562: Tech Brief 8: Problems and Solutions for the Year 2000 - DS12885, DS12887, DS12C887
  		• Application Note 701: Using the DS32kHz with Dallas Real-Time Clocks - DS12885
  		• Application Note 1145: Interface a Multiplexed-Bus Real-Time Clock to a µP With Separate Address and Data Buses - DS12885, DS12C887A, DS12887, DS12887A, DS12C887
  		• Application Note 3778: Problems and Solutions for Adjusting to Changes in Daylight Saving Time - DS12C887, DS12C887A, DS12885, DS12887, DS12887A
  		• Application Note 3816: Selecting a Backup Source for Real-Time Clocks - DS12885

    Design Guides
  		• Real-Time Clocks (PDF)

    Reliability Reports
  		• Reliability Report: DS12885.pdf DS12887.pdf DS12C887.pdf
  		• Request Reliability Report for:
  		• Underwriters Laboratories (UL®) Recognized

    Software/Models
    none

    Ordering Information
    Notes:

    1. Other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales.
    2. Didn't Find What You Need? Ask our applications engineers. Expert assistance in finding parts, usually within one business day.
    3. Part number suffixes: T or T&R = tape and reel;+ = RoHS/lead-free;# = RoHS/lead-exempt. More: SeeFull Data Sheet or Part Naming Conventions.
    4. * Some packages have variations, listed on the drawing. "PkgCode/Variation" tells which variation the product uses. Note that "+", "#", "-" in the part number suffix describes RoHS status. Package drawings may show a different suffix character.


    Devices: 1-28 of 28

    DS12885 Free
    Sample    		 Buy Status Recommended Replacement
    Package: TYPE PINS FOOTPRINT
      DRAWING CODE/VAR *
    		Temp RoHS/Lead-Free?
    Materials Analysis
    DS12885N     N/A No Longer Available DS12885N+
    		 PDIP(W);24 pin;520 mm²
    Outline Drawing: 21-0044 (PDF)
    Land Pattern: Not Applicable
    Use pkgcode/variation: P24-4*
    		-40°C to +85°C RoHS/Lead-Free: No
    Materials Analysis
    DS12885  
    		Active
    		PDIP(W);24 pin;520 mm²
    Outline Drawing: 21-0044 (PDF)
    Land Pattern: Not Applicable
    Use pkgcode/variation: P24-4*
    		0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    DS12885+  
    		Active
    		PDIP(W);24 pin;520 mm²
    Outline Drawing: 21-0044 (PDF)
    Land Pattern: Not Applicable
    Use pkgcode/variation: P24+4*
    		0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS12885N+    
    		Active
    		PDIP(W);24 pin;520 mm²
    Outline Drawing: 21-0044 (PDF)
    Land Pattern: Not Applicable
    Use pkgcode/variation: P24+4*
    		-40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS12885Q/T&R     N/A No Longer Available DS12885Q+
    		 PLCC;28 pin;158 mm²
    Outline Drawing: 21-0049 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: Q28-1*
    		0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    DS12885QN     N/A No Longer Available DS12885QN+
    		 PLCC;28 pin;158 mm²
    Outline Drawing: 21-0049 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: Q28-1*
    		-40°C to +85°C RoHS/Lead-Free: No
    Materials Analysis
    DS12885Q  
    		Active
    		PLCC;28 pin;158 mm²
    Outline Drawing: 21-0049 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: Q28-1*
    		0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    DS12885Q+  
    		Active
    		PLCC;28 pin;158 mm²
    Outline Drawing: 21-0049 (PDF)
    Land Pattern: 90-0235 (PDF)
    Use pkgcode/variation: Q28+2*
    		0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS12885Q+T&R    
    		Active
    		PLCC;28 pin;158 mm²
    Outline Drawing: 21-0049 (PDF)
    Land Pattern: 90-0235 (PDF)
    Use pkgcode/variation: Q28+2*
    		0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS12885QN+    
    		Active
    		PLCC;28 pin;158 mm²
    Outline Drawing: 21-0049 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: Q28+1*
    		-40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS12885QN+T&R    
    		Active
    		PLCC;28 pin;158 mm²
    Outline Drawing: 21-0049 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: Q28+1*
    		-40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS12885SN+T&R    
    		Active
    		SOIC(W);24 pin;166 mm²
    Outline Drawing: 21-0042 (PDF)
    Land Pattern: 90-0182 (PDF)
    Use pkgcode/variation: W24+1*
    		-40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS12885S    
    		Active
    		SOIC(W);24 pin;166 mm²
    Outline Drawing: 21-0042 (PDF)
    Land Pattern: 90-0182 (PDF)
    Use pkgcode/variation: W24-1*
    		0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    DS12885S+  
    		Active
    		SOIC(W);24 pin;166 mm²
    Outline Drawing: 21-0042 (PDF)
    Land Pattern: 90-0182 (PDF)
    Use pkgcode/variation: W24+1*
    		0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS12885S+T&R    
    		Active
    		SOIC(W);24 pin;166 mm²
    Outline Drawing: 21-0042 (PDF)
    Land Pattern: 90-0182 (PDF)
    Use pkgcode/variation: W24+1*
    		0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS12885SN     N/A No Longer Available DS12885SN+
    		 SOIC(W);24 pin;166 mm²
    Outline Drawing: 21-0042 (PDF)
    Land Pattern: 90-0182 (PDF)
    Use pkgcode/variation: W24-1*
    		-40°C to +85°C RoHS/Lead-Free: No
    Materials Analysis
    DS12885SN+    
    		Active
    		SOIC(W);24 pin;166 mm²
    Outline Drawing: 21-0042 (PDF)
    Land Pattern: 90-0182 (PDF)
    Use pkgcode/variation: W24+1*
    		-40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS12885T  
    		Active
    		TQFP;32 pin;85 mm²
    Dwg: 21-0292
    Land Pattern: Not Available
    Use pkgcode/variation: C32-3*
    		0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    DS12885T+  
    		Active
    		TQFP;32 pin;85 mm²
    Dwg: 21-0292
    Land Pattern: Not Available
    Use pkgcode/variation: C32+3*
    		0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS12885TN+    
    		Active
    		TQFP;32 pin;85 mm²
    Dwg: 21-0292
    Land Pattern: Not Available
    Use pkgcode/variation: C32+3*
    		-40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS12887 Free
    Sample    		 Buy Status Recommended Replacement
    Package: TYPE PINS FOOTPRINT
      DRAWING CODE/VAR *
    		Temp RoHS/Lead-Free?
    Materials Analysis
    DS12887  
    		Active
    		EDIP;24 pin;545 mm²
    Outline Drawing: 21-0241 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: MDP24-1*
    		0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    DS12887+  
    		Active
    		EDIP;24 pin;545 mm²
    Outline Drawing: 21-0241 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: MDP24+1*
    		0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS12887A Free
    Sample    		 Buy Status Recommended Replacement
    Package: TYPE PINS FOOTPRINT
      DRAWING CODE/VAR *
    		Temp RoHS/Lead-Free?
    Materials Analysis
    DS12887A  
    		Active
    		EDIP;24 pin;545 mm²
    Outline Drawing: 21-0241 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: MDP24-1*
    		0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    DS12887A+  
    		Active
    		EDIP;24 pin;545 mm²
    Outline Drawing: 21-0241 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: MDP24+1*
    		0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS12C887 Free
    Sample    		 Buy Status Recommended Replacement
    Package: TYPE PINS FOOTPRINT
      DRAWING CODE/VAR *
    		Temp RoHS/Lead-Free?
    Materials Analysis
    DS12C887  
    		Active
    		EDIP;24 pin;545 mm²
    Outline Drawing: 21-0241 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: MDP24-1*
    		0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    DS12C887+  
    		Active
    		EDIP;24 pin;545 mm²
    Outline Drawing: 21-0241 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: MDP24+1*
    		0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS12C887A Free
    Sample    		 Buy Status Recommended Replacement
    Package: TYPE PINS FOOTPRINT
      DRAWING CODE/VAR *
    		Temp RoHS/Lead-Free?
    Materials Analysis
    DS12C887A    
    		Active
    		EDIP;24 pin;545 mm²
    Outline Drawing: 21-0241 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: MDP24-1*
    		0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    DS12C887A+  
    		Active
    		EDIP;24 pin;545 mm²
    Outline Drawing: 21-0241 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: MDP24+1*
    		0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis

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    2007-03-26
    This page last modified: 2009-05-15


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