DS1321E+T&R

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.
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
• 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