12-5
August 1997
ICM7170
Microprocessor-Compatible, Real-Time Clock
Features
8-Bit,
μ
P 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
μ
A Typical at 3.0V
and 32kHz Crystal
Applications
Portable and Personal Computers
Data Logging
Industrial Control Systems
Point Of Sale
Description
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
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.
overhead
with
most
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.
Ordering Information
PART NUMBER
TEMP. RANGE
(
o
C)
PACKAGE
PKG.
NO.
ICM7170IPG
-40 to 85
24 Ld PDIP
E24.6
ICM7170IDG
-40 to 85
24 Ld SBDIP
D24.6
ICM7170IBG
-40 to 85
24 Ld SOIC
M24.3
ICM7170MDG
-55 to 125
24 Ld SBDIP
D24.6
ICM7170AIPG
-40 to 85
24 Ld PDIP
E24.6
ICM7170AIDG
-40 to 85
24 Ld SBDIP
D24.6
ICM7170AIBG
-40 to 85
24 Ld SOIC
M24.3
ICM7170AMDG
-55 to 125
24 Ld SBDIP
D24.6
NOTE:
“A” Parts Screened to <5
μ
A I
STBY
at 32kHz.
File Number
3019.3
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
http://www.intersil.com or 407-727-9207
|
Copyright
Intersil Corporation 1999
[ /Title
(ICM7
170)
/Sub-
ject
(Micro
proces-
sor-
Com-
pati-
ble,
Real-
Time
Clock)
/Autho
r ()
/Key-
words
(Inter-
sil
Corpo-
ration,
Real
Time
Clock,
Bat-
tery
Backu
p,
Inter-
nal
Oscil-
lator,
Micro-
proces-
sor
inter-
face,
Data