The DS1321 Flexible Nonvolatile Controller with Lithium Battery Monitor is a CMOS circuit which solves the application problem of converting CMOS SRAMs into nonvolatile memory. Incoming power is monitored for an out-of-tolerance condition. When such a condition is detected, chip enable outputs are inhibited to accomplish write protection and the battery is switched on to supply the SRAMs with uninterrupted power. Special circuitry uses a low-leakage CMOS process which affords precise voltage detection at extremely low battery consumption. One DS1321 can support as many as four SRAMs arranged in any of three memory configurations.

In addition to battery-backup support, the DS1321 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 DS1321 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.
DS1321:功能原理框图 DS1321:功能原理框图 放大+


  • 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
  • Flexible memory organization
    • Mode 0: 4 banks with 1 SRAM each
    • Mode 1: 2 banks with 2 SRAMs each
    • Mode 2: 1 bank with 4 SRAMs each
  • 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
  • Resets processor when power failure occurs and holds processor in reset during system power-up
  • Optional 5% or 10% power-fail detection
  • 16-pin PDIP, 16-pin SO and 20-pin TSSOP packages
  • Industrial temperature range of -40°C to +85°C

请查看具体的参数规格 Non-Volatile RAM Controllers (6)

Part NumberCE Cntrl.Smart Socket w/Int. Batt.Li Batt. MonitorPwr. Fail OutRAMs ControlledVSUPPLY
Package/PinsOper. Temp.
See Notes
DS1321 YesNoYesYes45
SOIC (N)/16
-40 to +85$5.52 @1k

Pricing Notes:


应用笔记 3254 Battery Monitoring in NV SRAM Modules
应用笔记 202 NV SRAM Frequently Asked Questions


产品可靠性报告: DS1321.pdf 
型号   生产流程   工艺   样本量   不合格   FIT @ 25°C   FIT @ 55°C   Material Composition  

备注: 通过技术手段对故障率进行汇总,并映射到相关的材料部件号。 故障率与被测件的数量密切相关。

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类型 编号 标题
应用笔记 3254 Battery Monitoring in NV SRAM Modules
应用笔记 202 NV SRAM Frequently Asked Questions