M40SZ100W

The M40SZ100Y/W NVRAM Controller is a selfcontained device which converts a standard lowpower SRAM into a non-volatile memory. A precision voltage reference and comparator monitors the V_CC input for an out-of-tolerance condition.

When an invalid V_CC condition occurs, the conditioned chip enable output (E_CON) is forced inactive to write protect the stored data in the SRAM. During a power failure, the SRAM is switched from the V_CC pin to the lithium cell within the SNAPHAT (or external battery for the 16-lead SOIC) 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, 330 mil SOIC provides sockets with gold plated contacts for direct connection to a separate SNAPHAT^® housing containing the battery. The SNAPHAT housing has gold plated pins which mate with the sockets, ensuring reliable connection. The housing is keyed to prevent improper insertion. This unique design allows the SNAPHAT battery package to be mounted on topof the SOIC package after the completion of the surface mount process which greatly reduces the board manufacturing process complexity of either directly soldering or inserting a battery into a soldered holder. Providing non-volatility becomes a "SNAP." This feature is also available in the "topless" 16-pin SOIC package (MQ).

Insertion of the SNAPHAT housing after reflow prevents potential battery damage due to the high temperatures required for device surface-mounting. The SNAPHAT housing is also keyed to prevent reverse insertion.

The 28-pin SOIC and battery packages are shipped separately in plastic anti-static tubes or in Tape & Reel form. For the 28-lead SOIC, the battery/ crystal package (e.g., SNAPHAT) part number is "M4ZXX-BR00SH" (see Table 13, page 17). Caution: Do not place the SNAPHAT battery top in conductive foam, as this will drain the lithium button-cell battery.