General Description

The DS1318 parallel-interface elapsed time counter

(ETC) is a 44-bit counter that maintains the amount of

time that the device operates from main and/or backup

power or during an external event. The internal

frequency of the counter clock is 4.096kHz, which pro-

vides a 244µs resolution and a maximum count of over

136 years. A built-in power-sense circuit detects power

failures, automatically switches to the backup supply,

and controls the timer. If an external event timer is

desired, the control input EXT can control the counter

operation. An open-drain output provides an interrupt,

and a square-wave output provides a programmable

square wave. The DS1318 is accessed through a byte-

wide parallel interface, and operates over the industrial

temperature range.

Applications

Power Meters

Industrial Controls

Servers

Features

♦ Byte-Wide Parallel Interface

♦ 44-Bit Binary Counter Provides Timer with 244µs

Resolution

♦ Automatic Power-Fail Detect and Switch Circuitry

Selects Power Source from the Primary Power

and the Battery, and Write Protects the Internal

Registers

♦ Internal Power-Fail Circuit Allows Timer to

Provide Primary or Battery Operation Times

♦ Timer can Alternately Provide an Event Timer of

Either an Active-High or Active-Low Pulse

♦ Interrupt Output Generated Periodically or When

the Upper 32 Bits of the Counter Match an Alarm

Register

♦ Square-Wave Output with 16 Selectable

Frequencies from 32.768kHz to 0.5Hz

♦ +3.3V Operation

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

Parallel-Interface Elapsed Time Counter

______________________________________________ Maxim Integrated Products

1

DS1318

GND

24

23

22

21

20

19

18

17

16

15

X1

TOP VIEW

X2

WE

OE

CE

DQ7

DQ6

DQ5

DQ4

DQ3

TSSOP

DQ2

DQ1

DQ0

A0

A1

A2

A3

1

2

3

4

5

10

9

8

7

6

11

12

14

13

SQW

IRQ

EXT

GND

Pin Configuration

Ordering Information

DS1318

CPU

DQ–DQ7

A3–A0

GND

RPU

SQW

X1

IRQ

WE

OE

CE

X2

EXT

EXTERNAL

COUNTER

ENABLE

(EVENT TIMER)

0.1

µF

Typical Operating Circuit

Rev 0; 2/04

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.

PART

TEMP RANGE

PIN-

PACKAGE

TOP MARK

DS1318

-40°C to +85°C

24 TSSOP,

4.4mm

DS1318