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GENERAL DESCRIPTION

The DS1338 serial real-time clock (RTC) is a low-

power,

full

binary-coded

decimal

(BCD)

clock/calendar plus 56 bytes of NV SRAM. Address

interface. The clock/calendar provides seconds,

minutes, hours, day, date, month, and year

information. 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 24-hour or 12-hour format with

AM/PM indicator. The DS1338 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)

TYPICAL OPERATING CIRCUIT

FEATURES



RTC Counts Seconds, Minutes, Hours, Date

of the Month, Month, Day of the Week, and

Year with Leap-Year Compensation Valid Up

to 2100



Available in a Surface-Mount Package with an

Integrated Crystal (DS1338C)



56-Byte Battery-Backed General-Purpose

RAM with Unlimited Writes





Programmable Square-Wave Output Signal



Automatic Power-Fail Detect and Switch

Circuitry



-40°C to +85°C Operating Temperature Range



Underwriters Laboratories (UL) Recognized

ORDERING INFORMATION

PART

TEMP RANGE

PIN-PACKAGE

TOP MARK†

DS1338Z-18+

-40°C to +85°C

8 SO (0.150″)

DS1338-18

DS1338Z-3+

-40°C to +85°C

8 SO (0.150″)

DS1338-3

DS1338Z-33+

-40°C to +85°C

8 SO (0.150″)

DS133833

DS1338U-18+

-40°C to +85°C

8 µSOP

1338

rr-18

DS1338U-3+

-40°C to +85°C

8 µSOP

1338

rr-3

DS1338U-33+

-40°C to +85°C

8 µSOP

1338

rr-33

DS1338C-18#

-40°C to +85°C

16 SO (0.300″)

DS1338C-18

DS1338C-3#

-40°C to +85°C

16 SO (0.300″)

DS1338C-3

DS1338C-33#

-40°C to +85°C

16 SO (0.300″)

DS1338C-33

rr = second line, revision level

+ Denotes a lead(Pb)-free/RoHS-compliant device.

# Denotes a RoHS-compliant device that may include lead that is

exempt under the RoHS requirements. The lead finish is JESD97

category e3, and is compatible with both lead-based and lead-free

soldering processes.

† A “+” anywhere on the top mark denotes a lead-free device. A “#”

denotes a RoHS-compliant device.

Pin Configurations appear at end of data sheet.

DS1338

CPU

SDA

SCL

GND

X2

X1

CRYSTAL

SQW/OUT

i

R

DS1338

19-6019; Rev 3/12