General Description

The low-voltage serial-peripheral interface (SPI™)

DS1390/DS1391 and the low-voltage 3-wire DS1392/

DS1393 real-time clocks (RTCs) are clocks/calendars

that provide hundredths of a second, seconds, min-

utes, hours, day, date, month, and year information.

The date at the end of the month 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 an AM/PM indicator.

One programmable time-of-day alarm is provided. A

temperature-compensated voltage reference monitors

backup supply if a power failure is detected. On the

DS1390, a single open-drain output provides a CPU

interrupt or a square wave at one of four selectable fre-

quencies. The DS1391 replaces the SQW/INT pin with a

RST output/debounced input.

The DS1390 and DS1391 are programmed serially

through an SPI-compatible, bidirectional bus. The

DS1392 and DS1393 communicate over a 3-wire serial

bus, and the extra pin is used for either a separate

interrupt pin or a RST output/debounced input.

All four devices are available in a 10-pin µSOP package,

and are rated over the industrial temperature range.

Applications

Hand-Held Devices

GPS/Telematics Devices

Embedded Time Stamping

Medical Devices

Features

♦ Real-Time Clock Counts Hundredths of Seconds,

Seconds, Minutes, Hours, Day, Date, Month, and

Year with Leap-Year Compensation Valid Up to

2100

♦ Output Pin Configurable as Interrupt or Square

Wave with Programmable Frequency of

32.768kHz, 8.192kHz, 4.096kHz, or 1Hz

(DS1390/DS1393 Only)

♦ One Time-of-Day Alarm

♦ Power-Fail Detect and Switch Circuitry

♦ Reset Output/Debounced Input (DS1391/DS1393)

♦ Separate SQW and INT Output (DS1392)

♦ Trickle-Charge Capability

♦ SPI Supports Modes 1 and 3 (DS1390/DS1391)

♦ 3-Wire Interface (DS1392/DS1393)

♦ 4MHz at 3.0V and 3.3V

♦ 1MHz at 1.8V

♦ Three Operating Voltages: 1.8V ±5%, 3.0V ±10%,

and 2.97 to 5.5V

♦ Industrial Temperature Range: -40°C to +85°C

♦ Underwriters Laboratory (UL) Recognized

Low-Voltage SPI/3-Wire RTCs with

Trickle Charger

______________________________________________ Maxim Integrated Products

1

Ordering Information

Rev 0; 7/04

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

Typical Operating Circuits and Pin Configurations appear at

end of the data sheet.

Where “rr” is a revision code on the second line of the top mark.

PART

TEMP RANGE

PIN-

PACKAGE

TOP MARK

DS1390U-18

-40°C to +85°C

10 µSOP

DS1390 rr-18

DS1390U-3

-40°C to +85°C

10 µSOP

DS1390 rr-3

DS1390U-33

-40°C to +85°C

10 µSOP

DS1390 rr-33

DS1391U-18

-40°C to +85°C

10 µSOP

DS1391 rr-18

DS1391U-3

-40°C to +85°C

10 µSOP

DS1391 rr-3

DS1391U-33

-40°C to +85°C

10 µSOP

DS1391 rr-33

DS1392U-18

-40°C to +85°C

10 µSOP

DS1393 rr-18

DS1392U-3

-40°C to +85°C

10 µSOP

DS1392 rr-3

DS1392U-33

-40°C to +85°C

10 µSOP

DS1392 rr-33

DS1393U-18

-40°C to +85°C

10 µSOP

DS1393 rr-18

DS1393U-3

-40°C to +85°C

10 µSOP

DS1393 rr-3

DS1393U-33

-40°C to +85°C

10 µSOP

DS1393 rr-33

SPI is a trademark of Motorola, Inc.