The DS1643P-100+ is a non-volatile timekeeping RAM in 34 pin PWRCP (PowerCap) module package. This device is 8k x 8 static RAM with fully functional real time clock (RTC) which can be accessible in a bytewide format. It can be easily substituted in ROM and EEPROM sockets providing read/write non-volatility and the addition of the real time clock function. The RTC registers contain year, month, date, day, hours, minutes and seconds data in 24-hour BCD format. Corrections for the day of the month and leap year are made automatically. The RTC clock registers are double-buffered to avoid access of incorrect data that can occur during clock update cycles. DS1643 contains its own power-fail circuitry which deselects the device when the VCC supply is in an out of tolerance condition. This feature prevents loss of data from unpredictable system operation brought on by low VCC as errant access and update cycles are avoided.
Supply voltage range is 4.5V to 5.5V
Operating temperature range from 0°C to 70°C
Standard JEDEC bytewide 8k x 8 static RAM pin-out
Clock registers are accessed identically to the static RAM
Non-volatile with over 10 years of operation in the absence of power
Access time is 100ns
Power-fail write protection allows for ±10% VCC power supply tolerance
Lithium energy source is electrically disconnected until power is applied for first time
