DS1308 Datasheet, PDF(1/16 Page) Dallas Semiconductor

19-6353; Rev 0; 5/12

DS1308

Low-Current I2C RTC with 56-Byte NV RAM

General Description

The DS1308 serial real-time clock (RTC) is a low-power,

full binary-coded decimal (BCD) clock/calendar plus

56 bytes of NV RAM. Address and data are transferred

serially through an I2C interface. The clock/calendar

provides seconds, minutes, hours, day, date, month,

and year information. The end of the month date is auto-

matically adjusted for months with fewer than 31 days,

including corrections for leap year. The clock operates

in either the 24-hour or 12-hour format with an AM/PM

indicator. The DS1308 has a built-in power-sense circuit

that detects power failures and automatically switches to

the backup supply, maintaining time and date operation.

Applications

Handhelds (GPS, POS Terminal)

Consumer Electronics (Set-Top Box, Digital

Recording, Network Appliance)

Office Equipment (Fax/Printer, Copier)

Medical (Glucometer, Medicine Dispenser)

Telecommunications (Router, Switcher, Server)

Other (Utility Meter, Vending Machine,

Thermostat, Modem)

Ordering Information appears at end of data sheet.

Features

S Low Timekeeping Current of 250nA (typ)

S Compatible with Crystal ESR Up to 100kÏ

S RTC Counts Seconds, Minutes, Hours, Date,

Month, Day of the Week, and Year with Leap-Year

Compensation Up to 2400

S 56-Byte, Battery-Backed, General-Purpose RAM

with Unlimited Writes

S I2C Serial Interface

S External Clock Source for Synchronization Clock

Reference (e.g., 32kHz, 50Hz/60Hz Powerline, GPS

1PPS)

S Programmable Square-Wave Output Signal

S Automatic Power-Fail Detect and Switch Circuitry

S -40NC to +85NC Operating Temperature Range

S Underwriters Laboratories (UL) Recognized

Typical Operating Circuit

VCC

RPU RPU RPU

CPU

VCC

SCL

SDA

SQW/CLKIN

DS1308

VBAT

GND

For related parts and recommended products to use with this part, refer to: www.maxim-ic.com/DS1308.related

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maximâs website at www.maxim-ic.com.

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