Controller Converts Low-Power SRAMs Into NVRAMs

Designed for 3.3V operation, the M48T201V controller provides all the functionality of firm's Timekeeper RTCs, including a power-fail control circuit, a lithium cell, a real-time clock circuit with alarms and a quartz crystal, but allows the user to employ an external low-power SRAM for lower system cost. The 5V version of the device, the M48T201Y, is complemented by the M68Z128, the first in a family of ultra-low power SRAMs optimized for use with NVRAM controller chips. The 3.3V LPSRAM, which complements the M48T201V, is also sampling. A key benefit of the M48T201V is the addition of an 8-bit Century Register, giving a fully Y2K-compliant, 4-digit year. Other major features include a watchdog timer, power-on reset, programmable alarms and a battery-low flag. Access time, when the device is used in conjunction with a 70-ns LPSRAM, is 85 ns typically.