The CMOS bq4015/Y/LY is a nonvolatile 4,194,304-bit static RAM organized as 524,288 words by 8 bits. The integral control circuitry and lithium energy source provide reliable nonvolatility coupled with the unlimited write cycles of standard SRAM.

The control circuitry constantly monitors the single supply for an out-of-tolerance condition. When V_CC falls out of tolerance, the SRAM is unconditionally write-protected to prevent an inadvertent write operation.

At this time the integral energy source is switched on to sustain the memory until after V_CC returns valid.

The bq4015/Y/LY uses extremely low standby current CMOS SRAMs, coupled with small lithium coin cells to provide nonvolatility without long write-cycle times and the write-cycle limitations associated with EEPROM.