RTC Module With 8Kx8 NVSRAM Watchdog Timer UP Reset Interrupts And Battery Low Warning
The BQ4822Y RTC Module is a non-volatile 65,536-bit SRAM organized as 8192 words by 8 bits with an integral Real-Time Clock and CPU supervisor The CPU supervisor provides a programmable watchdog Timer and a Microprocessor reset. Other features include an alarm, power-fail and periodic interrupt, and a battery low warning.
The device combines an internal lithium battery, quartz crystal, Clock and power-fail chip, and a full CMOS SRAM in a plastic 28-pin DIP module. The RTC Module directly replaces industry-standard SRAMs and also fits into many EPROM and EEPROM sockets without any requirement for special write Timing or limitations on the number of write cycles.
Registers for the Real-Time Clock alarm and other special functions are located in Registers 1FF0h1FFFh of the memory array.
The Clock and alarm Registers 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 SRAM array.
The BQ4822Y also contains a power-fail-detect circuit. The circuit deselects the device whenever VCC falls below tolerance, providing a high degree of data security. The battery is electrically isolated when shipped from the factory to provide maximum battery capacity. The battery remains disconnected until the first application of VCC.
By Texas Instruments
|BQ4822YMA-70||Texas Instruments||0 TIMER(S), REAL TIME CLOCK, PDIP28, PLASTIC, DIP-28|
|BQ4822Y Pb-Free||BQ4822Y Cross Reference||BQ4822Y Schematic||BQ4822Y Distributor|
|BQ4822Y Application Notes||BQ4822Y RoHS||BQ4822Y Circuits||BQ4822Y footprint|