bq4850Y

The bq4850Y RTC Module is a nonvolatile 4,194,304-bit SRAM organized as 524,288 words by 8 bits with an integral accessible real-time clock.


The bq4850Y combines an internal lithium battery, quartz crystal, clock and power-fail chip, and a full CMOS SRAM in a plastic 32-pin DIP module. The RTC Module directly replaces industry-standard SRAMs andalso fits into many EPROM and EE-PROM sockets without any requirement for special write timing or limitation son the number of write cycles.


Registers for the real-time clock, alarm and other special functions of bq4850Y are located in registers 7FFF8h1FFFFhofthememoryarray.


The clock and alarm registers of bq4850Y are dual-port read/write SRAM locations that are updated once per second by a clock control circuit from the internal clock counters. The dual-port registers allow clock updates to occur without interrupting normal access to the rest of the SRAMarray.


The bq4850Y also contains a powerfail-detect circuit. The circuit deselects the device whenever V_CC falls below tolerance,providing a high degree of data security. The battery of bq4850Y is electrically isolated when shipped from the factory to provide maximum battery capacity. The battery remains disconnected until the first applicationofV_CC.