DS12R885:RTCs with Constant-Voltage Trickle Charger

The DS12R885 is a functional drop-in replacement for the DS12885 real-time clock (RTC). The device provides an RTC/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. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including correction for leap years. It also operates 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. The VBACKUP pin supports a rechargeable battery or a super cap and includes an integrated, always enabled trickle charger. The DS12R885 is accessed through a multiplexed byte-wide interface, which supports both Intel and Motorola modes. The DS12CR887 and DS12R887 integrate the DS12R885 die with a crystal and battery.

Key Features
  • Trickle-Charge Capability for a Rechargeable Battery or Super Cap
  • Selectable Intel or Motorola Bus Timing
  • RTC Counts Seconds, Minutes, Hours, Day, Date, Month, and Year with Leap-Year Compensation to 2100
  • Interrupt Output with Three Independently Maskable Interrupt Flags
  • Time-of-Day Alarm is Once-per-Second to Once-per-Day
  • Periodic Rates from 122µs to 500ms
  • End-of-Clock Update Cycle Flag
  • 14 Bytes of Clock and Control Registers
  • 114 Bytes of General-Purpose Battery-Backed NV RAM with Clear Input
  • Programmable Square-Wave Output
  • Automatic Power-Fail Detect and Switch Circuitry
  • +5.0V or +3.3V Operation
  • Industrial Temperature Range
  • DS12CR887 Encapsulated DIP (EDIP) Module with Integrated Battery and Crystal
  • DS12R887 BGA Module Surface-Mountable Package with Integrated Crystal and Rechargeable Battery
DS12CR887, DS12R885, DS12R887: Typical Operating Circuit
DS12CR887, DS12R885, DS12R887: Typical Operating Circuit
Applications/Uses
  • Embedded Systems
  • Network Hubs, Switches, Routers
  • Security Systems
  • Utility Meters
DataSheet
titleDownload file
DS12CR887-DS12R887 Data SheetDS12CR887-DS12R887.pdf
Parametrics
Part NumberInterfaceVSUPPLY
(V)
Time Keeping Current
(nA)
CL
(pF)
Memory TypeMemory Size
(Bytes)
Time of Day AlarmsFunctionsPackage/PinsBudgetary
Price
typSee Notes
DS12CR887Multiplexed3.3
5
--NV SRAM1141RTCEDIP/24$6.23 @1k
DS12R88580012.5SOIC(W)/24$1.80 @1k
Quality and Environmental Data
Ordering Information
Part NumberStatusRecommended ReplacementPackageTempRoHS
DS12R885S-33+ActiveSOIC(W),;24 pin;166.1 mm²-40°C to +85°CLead Free
DS12R885S-33+T&RActiveSOIC(W),;24 pin;166.1 mm²-40°C to +85°CLead Free
DS12R885S-5+ActiveSOIC(W),;24 pin;166.1 mm²-40°C to +85°CLead Free
DS12R885S-5+T&RActiveSOIC(W),;24 pin;166.1 mm²-40°C to +85°CLead Free
DS12CR887-DS12R887.pdf DS12R885
DS12CR887-DS12R887_cn.pdf DS12R885
Tips for Writing Bulletproof Real-Time Clock Control Code DS3234
State Machine Logic in Binary-Coded Decimal (BCD)-Formatted Real-Time Clocks DS3234
Oscillator Design Considerations for Low-Current Applications DS17885
Selecting a Backup Source for Real-Time Clocks DS3234
Calculating ML Cell Life for an RTC Backup Operation DS12R885
Problems and Solutions for Adjusting to Changes in Daylight Saving Time DS17887
Interface a Multiplexed-Bus Real-Time Clock to a µP With Separate Address and Data Buses DS17887
Using the DS32kHz with Maxim Real-Time Clocks DS17885
Using Multiplexed Bus Clocks with a Microcontroller DS17887
Lithium Coin-Cell Batteries: Predicting an Application Lifetime DS9034PCX
Design Considerations for Maxim Real-Time Clocks DS3234
Crystal Considerations with Maxim Real-Time Clocks (RTCs) DS3234
DS12R885.pdf DS12R885
DS12CR887-DS12R887_cn.pdf DS12R885