1

®

FN3019.6

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

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ICM7170

Microprocessor-Compatible,

Real-Time Clock

The ICM7170 real time clock is a microprocessor bus

compatible peripheral, fabricated using Intersil’s silicon gate

CMOS LSl process. An 8-bit bidirectional bus is used for the

data I/O circuitry. The clock is set or read by accessing the 8

internal separately addressable and programmable counters

a pulse train divided down from a crystal oscillator circuit,

and the frequency of the crystal is selectable with the

on-chip command register. An extremely stable oscillator

frequency is achieved through the use of an on-chip

regulated power supply.

for wait states or software overhead with most

microprocessors. Furthermore, an ALE (Address Latch

Enable) input is provided for interfacing to microprocessors

with a multiplexed address/data bus. With these two special

features, the ICM7170 can be easily interfaced to any

available microprocessor.

The ICM7170 generates two types of interrupts, periodic and

alarm. The periodic interrupt (100Hz, 10Hz, etc.) can be

programmed by the internal interrupt control register to

provide 6 different output signals. The alarm interrupt is set

by loading an on-chip 51-bit RAM that activates an interrupt

output through a comparator. The alarm interrupt occurs

when the real time counter and alarm RAM time are equal. A

status register is available to indicate the interrupt source.

An on-chip Power Down Detector eliminates the need for

external components to support the battery back-up

function. When a power down or power failure occurs,

internal logic switches the on-chip counters to battery back-

up operation. Read/write functions become disabled and

operation is limited to time-keeping and interrupt generation,

resulting in low power consumption.

Internal latches prevent clock roll-over during a read cycle.

Counter data is latched on the chip by reading the

100th-seconds counter and is held indefinitely until the

counter is read again, assuring a stable and reliable time

value.

Features

• 8-Bit,

µP Bus Compatible

- Multiplexed or Direct Addressing

• Regulated Oscillator Supply Ensures Frequency Stability

and Low Power

• Time From 1/100 Seconds to 99 Years

• Software Selectable 12/24 Hour Format

• Latched Time Data Ensures No Roll Over During Read

• Full Calendar with Automatic Leap Year Correction

• On-Chip Battery Backup Switchover Circuit

• Access Time Less than 300ns

• 4 Programmable Crystal Oscillator Frequencies Over

Industrial Temperature Range

• 3 Programmable Crystal Oscillator Frequencies Over

Military Temperature Range

• On-Chip Alarm Comparator and RAM

• Interrupts from Alarm and 6 Selectable Periodic Intervals

• Standby Micro-Power Operation: 1.2

µA Typical at 3.0V

and 32kHz Crystal

Applications

• Portable and Personal Computers

• Data Logging

• Industrial Control Systems

• Point Of Sale

Related Literature

• Technical Brief TB363 “Guidelines for Handling and

Processing Moisture Sensitive Surface Mount Devices

(SMDs)”

Part Number Information

PART NUMBER

TEMP. RANGE

PACKAGE

PKG.

NO.

ICM7170IPG

-40× to 85×

24 Ld PDIP

E24.6

ICM7170IBG

-40× to 85×

24 Ld SOIC

M24.3

ICM7170AIPG

-40× to 85×

24 Ld PDIP

E24.6

ICM7170AIBG

-40× to 85×

24 Ld SOIC

M24.3

NOTE: “A” Parts Screened to <5

Data Sheet

November 2003

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