DESCRIPTION

The DS1642 is a 2K x 8 nonvolatile static RAM and a full-function real time clock which are both accessible in a bytewide format. The nonvolatile time keeping RAM is pin- and function-equivalent to any JEDEC standard 2K x 8 SRAM. The device can also be easily substituted in ROM, EPROM and EEPROM sockets, providing read/write nonvolatility and the addition of the real time clock function.

FEATURES

● Integrated NV SRAM, real time clock, crystal, power fail control circuit and lithium energy source

● Standard JEDEC bytewide 2K x 8 static RAM pinout

● Clock registers are accessed identically to the static RAM. These registers are resident in the eight top RAM locations

● Totally nonvolatile with over 10 years of operation in the absence of power

● Access times of 70 ns and 100 ns

● Quartz accuracy ±1 minute a month @ 25°C, factory calibrated

● BCD coded year, month, date, day, hours, minutes, and seconds with leap year compensation valid up to 2100

● Power-fail write protection allows for ±10 VCC power supply tolerance

● Lithium energy source is electrically disconnected to retain freshness until power is applied for the first time