DS1312:Nonvolatile Controller with Lithium Battery Monitor

The DS1312 Nonvolatile Controller with Battery Monitor is a CMOS circuit which solves the application problem of converting CMOS RAM into nonvolatile memory. Incoming power is monitored for an out-of-tolerance condition. When such a condition is detected, chip enable is inhibited to accomplish write protection and the battery is switched on to supply the RAM with uninterrupted power. Special circuitry uses a low-leakage CMOS process which affords precise voltage detection at extremely low battery consumption. In addition to battery-backup support, the DS1312 performs the important function of monitoring the remaining capacity of the lithium battery and providing a warning before the battery reaches end-of-life. Because the open-circuit voltage of a lithium backup battery remains relatively constant over the majority of its life, accurate battery monitoring requires loaded-battery voltage measurement. The DS1312 performs such measurement by periodically comparing the voltage of the battery as it supports an internal resistive load with a carefully selected reference voltage. If the battery voltage falls below the reference voltage under such conditions, the battery will soon reach end-of-life. As a result, the Battery Warning pin is activated to signal the need for battery replacement.

Key Features
  • Converts CMOS SRAM into nonvolatile memory
  • Unconditionally write-protects SRAM when VCC is out of tolerance
  • Automatically switches to battery backup supply when VCC power failure occurs
  • Monitors voltage of a lithium cell and provides advanced warning of impending battery failure
  • Signals low-battery condition on active low Battery Warning output signal
  • Optional 5% or 10% power-fail detection
  • Space-saving 8-pin DIP and SOIC packages
  • Optional 16-pin SOIC and 20-pin TSSOP versions reset processor when power failure occurs and hold processor in reset during system power-up
  • Industrial temperature range of -40°C to +85°C
DS1312: Functional Block Diagram
DS1312: Functional Block Diagram
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DS1312 Data SheetDS1312.pdf
Part NumberCE Cntrl.Smart Socket w/Int. Batt.Li Batt. MonitorPwr. Fail OutRAMs ControlledVSUPPLY
Package/PinsOper. Temp.
See Notes
-40 to +85$6.29 @1k
Quality and Environmental Data
Ordering Information
Part NumberStatusRecommended ReplacementPackageTempRoHS
DS1312No Longer AvailableDS1312+PDIP(N),;8 pin;79.7 mm²-40°C to +85°CNo
DS1312+ActivePDIP(N),;8 pin;79.7 mm²-40°C to +85°CLead Free
DS1312ENo Longer AvailableDS1312E+TSSOP,;20 pin;45.2 mm²-40°C to +85°CNo
DS1312E+ActiveTSSOP,;20 pin;45.2 mm²-40°C to +85°CLead Free
DS1312E+T&RActiveTSSOP,;20 pin;45.2 mm²-40°C to +85°CLead Free
DS1312E/T&RNo Longer AvailableDS1312E+T&RTSSOP,;20 pin;45.2 mm²-40°C to +85°CNo
DS1312SNo Longer AvailableDS1312S+SOIC(W),;16 pin;111.8 mm²-40°C to +85°CNo
DS1312S+ActiveSOIC(W),;16 pin;111.8 mm²-40°C to +85°CLead Free
DS1312S+T&RActiveSOIC(W),;16 pin;111.8 mm²-40°C to +85°CLead Free
DS1312S-2No Longer AvailableDS1312S-2+SOIC(N),;8 pin;30.9 mm²-40°C to +85°CNo
Part NumberStatusRecommended ReplacementPackageTempRoHS
DS1312S-2+ActiveSOIC(N),;8 pin;30.9 mm²-40°C to +85°CLead Free
DS1312S-2/T&RNo Longer AvailableDS1312S-2+T&RSOIC(N),;8 pin;30.9 mm²-40°C to +85°CNo
DS1312S/T&RNo Longer AvailableDS1312S+T&RSOIC(W),;16 pin;111.8 mm²-40°C to +85°CNo
DS1312.pdf DS1312
DS1312.pdf DS1312
DS1312.pdf DS1312
Battery Monitoring in NV SRAM Modules DS1350Y
NV SRAM Frequently Asked Questions DS1350Y
DS1312.pdf DS1312
DS1312.pdf DS1312