ICM7170_03 Datasheet, PDF (1/14 Pages) Intersil Corporation – Microprocessor-Compatible, Real-Time®lock

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November 2003
ICM7170
FN3019.6
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
from ¹/₁₀₀ seconds to years. The counters are controlled by
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.
The device access time (t_ACC) of 300ns eliminates the need
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.
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: 1.2µA 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)”
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.
Part Number Information
TEMP. RANGE
PART NUMBER
(^oC)
PACKAGE
ICM7170IPG
-40× to 85× 24 Ld PDIP
ICM7170IBG
-40× to 85× 24 Ld SOIC
ICM7170AIPG
-40× to 85× 24 Ld PDIP
ICM7170AIBG
-40× to 85× 24 Ld SOIC
NOTE: “A” Parts Screened to <5µA I_STBY at 32kHz.
PKG.
NO.
E24.6
M24.3
E24.6
M24.3
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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