The M48T18-100PC1, manufactured by STMicroelectronics, is a Parallel 64kbit NV SRAM with Real-Time Clock (RTC) circuit in a 28-pin plastic dual-in-line package. This device features a non-volatile clock/calendar circuit, with a clock operating from a 32 kHz crystal or external clock source. It provides year, month, date and century information, as well as day, hours, minutes and seconds. It has adjustable leap-year compensation and a programmable 12/24-hour format. The M48T18-100PC1 is operated with a power supply voltage range of 4.5V to 5.5V and has access time of 100ns.