Low-Current, SPI-Compatible Real-Time Clock

The DS1347 SPI-compatible real-time clock (RTC) contains a real-time clock/calendar and 31 x 8 bits of static random-access memory (SRAM). The real-time clock/calendar provides seconds, minutes, hours, day, date, month, year, and century information. A time/date programmable polled ALARM is included in the device. The end-of-the-month date is automatically adjusted for months with fewer than 31 days, including corrections for leap year. The clock operates in either the 24hr or 12hr format with an active-low AM/PM indicator. The device operates with a supply voltage of +2V to +5.5V, are available in the ultra-small 8-pin TDFN package, and work over the -40°C to +85°C industrial temperature range.

Applications

* Battery-Powered Products * Fax Machines * Intelligent Instruments * Point-of-Sale Equipment * Portable Instruments

* Completely Manages All Timekeeping Functions

* RTC Counts Seconds, Minutes, Hours, Day of Week, Date of Month, Month, Year, and Century

* Leap-Year Compensation

* 31 x 8-Bit SRAM for Scratchpad Data Storage

* Programmable Time/Date Polled ALARM Function

* Uses Standard 32.768kHz Watch Crystal

* Low-Power Operation Extends Battery Life

* Low Timekeeping Current (400nA at 2V)

* +2V to +5.5V Wide Operating Voltage Range

* Standard Serial Port Interfaces with Most Microcontrollers

* SPI (Mode 1 or 3) Interface: 4MHz at 5V, 1MHz at 2V

* Single-Byte or Multiple-Byte (Burst Mode) Data Transfer for Read or Write of Clock Registers or SRAM

* 3mm x 3mm x 0.8mm, 8-Pin TDFN Package Minimizes Required Space

* No External Crystal Bias Resistors or Capacitors Required