描述 Description

The M48T08/18/08Y TIMEKEEPER?RAM is an 8 K x 8 non-volatile static RAM and real-time clock which is pin and function compatible with the DS1643. The monolithic chip is available in two special packages to provide a highly integrated battery-backed memory and real-time clock solution.

The M48T08/18/08Y is a non-volatile pin and function equivalent to any JEDEC standard 8 K x 8 SRAM. It also easily fits into many ROM, EPROM, and EEPROM sockets, providing the non-volatility of PROMs without any requirement for special WRITE timing or limitations on the number of WRITEs that can be performed.

The 28-pin, 600 mil DIP CAPHAT? houses the M48T08/18/08Y silicon with a quartz crystal and a long-life lithium button cell in a single package.

The 28-pin, 330 mil SOIC provides sockets with gold-plated contacts at both ends for direct connection to a separate SNAPHAT? housing containing the battery and crystal. The unique design allows the SNAPHAT?battery package to be mounted on top of the SOIC package after the completion of the surface mount process. Insertion of the SNAPHAT?housing after reflow prevents potential battery and crystal damage due to the high temperatures required for device surface-mounting. The SNAPHAT?housing is keyed to prevent reverse insertion.

The SOIC and battery/crystal packages are shipped separately in plastic anti-static tubes or in tape & reel form. For the 28-lead SOIC, the battery/crystal package (e.g., SNAPHAT?) part number is “M4T28-BR12SH” or “M4T32-BR12SH”.

特性 Features

? Integrated ultra low power SRAM, real-time clock, power-fail control circuit, and battery
? BYTEWIDE?RAM-like clock access
? BCD coded year, month, day, date, hours, minutes, and seconds
? Typical clock accuracy of ±1 minute a month, at 25 °C
? Automatic power-fail chip deselect and WRITE protection
? WRITE protect VPFD= power-fail deselect voltage):
?M48T08: VCC= 4.75 to 5.5 V; 4.5 V ≤ VPFD≤ 4.75 V
?M48T18/T08Y: VCC= 4.5 to 5.5 V; 4.2 V ≤ VPFD≤ 4.5 V
? Software controlled clock calibration for high accuracy applications
? Self-contained battery and crystal in the CAPHAT?DIP package
? Packaging includes a 28-lead SOIC and SNAPHAT? top (to be ordered separately)
? SOIC package provides direct connection for a snaphat top which contains the battery and crystal
? Pin and function compatible with DS1643 and JEDEC standard 8 K x 8 SRAMs
? RoHS compliant
?Lead-free second level interconnect

簡介

M48T18屬于集成電路（IC）的實時時鐘。由制造生產(chǎn)的M48T18實時時鐘實時時鐘 (RTC) 為幾乎所有需要保持精確時間的電子設(shè)備提供時間和/或日期信息。時鐘類型有二進制計數(shù)器、時鐘/日歷/監(jiān)控器、歷時計時器、幻時鐘芯片、便攜式系統(tǒng)控制器、溫度記錄器、時間事件記錄器和計時器時鐘外設(shè)。其包含 2 B 至 2 MB 不等的存儲器，接口選項有 I2C、并行、串行、SPI、1 線式、2 線式、3 線式和 4 線式。