Description

The DS1747-70+ is a real-time clock/calendar (RTC) and nonvolatile static RAM integrated circuit with 512k x 8 memory size. It has a byte-wide interface, allowing user access to all registers. The RTC registers contain data in BCD format for century, year, month, date, day, hours, minutes, and seconds. It is Y2K compliant and automatically corrects for leap year and month variations. The DS1747-70+ is totally nonvolatile and features over 10 years of operation in the absence of power.

Specifications and features

• Integrated NV SRAM, RTC, Crystal, Power-Fail Control Circuit, and Lithium Energy Source
• Byte-wide interface accessing clock registers identically to static RAM
• RTC registers are in the eight uppermost RAM locations
• BCD-coded century, year, month, date, day, hours, minutes, and seconds with automatic leap year compensation valid up to the year 2100
• Battery voltage-level indicator flag
• Power-fail write protection allows for ±10% VCC power-supply tolerance
• Lithium energy source is electrically disconnected to retain freshness until power is applied for the first time
• DIP module is standard JEDEC byte-wide 512k x 8 static RAM pinout
• PowerCap module board is surface-mountable for direct connection to PowerCap containing battery and crystal
• Replaceable battery (PowerCap) and power-on reset output
• Pin-for-pin compatible with other densities of DS174xP timekeeping RAM
• Also available in industrial temperature range: -40°C to +85°C

Application Scenarios

The DS1747-70+ is ideal for applications that require a real-time clock/calendar and nonvolatile static RAM, such as point-of-sale terminals, ATMs, and utilities.

Comparison

• Y2K compliant and automatically corrects for month and leap year variations
• Totally nonvolatile with over 10 years of operation in the absence of power
• Integrated with NV SRAM, RTC, crystal, power-fail control circuit, and lithium energy source
• Byte-wide interface accessing clock registers identically to static RAM

• May not be suitable for applications that require larger memory sizes
• PowerCap module board is not included with the DIP module
• Requires a replaceable PowerCap battery