SUMMARY DESCRIPTION
The M40Z111/W NVRAM SUPERVISOR is a self-contained device which converts a standard lowpower SRAM into a non-volatile memory. A precision voltage reference and comparator monitors the VCC input for an out-of-tolerance condition.
When an invalid VCC condition occurs, the conditioned chip enable (ECON) output is forced inactive to write-protect the stored data in the SRAM.
During a power failure, the SRAM is switched from the VCC pin to the lithium cell within the SNAPHAT® to provide the energy required for data retention. On a subsequent power-up, the SRAM remains write protected until a valid power condition returns.
The 28-pin, 330mil SOIC provides sockets with gold plated contacts at both ends for direct connection to a separate SNAPHAT housing containing the battery. The unique design allows the SNAPHAT battery package to be mounted on top of the SOIC package after the completion of the surface mount process.

FEATURES SUMMARY
■ CONVERT LOW POWER SRAMs INTO NVRAMs
■ PRECISION POWER MONITORING and
   POWER SWITCHING CIRCUITRY
■ AUTOMATIC WRITE-PROTECTION WHEN
   VCC IS OUT-OF-TOLERANCE
■ CHOICE OF SUPPLY VOLTAGES and
   POWER-FAIL DESELECT VOLTAGES:
   – M40Z111: VCC = 4.5 to 5.5V
      THS = VSS; 4.5 ≤ VPFD ≤ 4.75V
      THS = VOUT; 4.2 ≤ VPFD ≤ 4.5V
   – M40Z111W: VCC = 3.0 to 3.6V
      THS = VSS; 2.8 ≤ VPFD ≤ 3.0V
      VCC = 2.7 to 3.3V
      THS = VOUT; 2.5 ≤ VPFD ≤ 2.7V
■ LESS THAN 15ns CHIP ENABLE ACCESS
   PROPAGATION DELAY (for 5.0V device)
■ PACKAGING INCLUDES A 28-LEAD SOIC and
   SNAPHAT® TOP (to be ordered separately)
■ SOIC PACKAGE PROVIDES DIRECT
   CONNECTION FOR A SNAPHAT TOP WHICH
   CONTAINS THE BATTERY