9-12
August 1997
ICM7217
4-Digit LED Display,
Programmable Up/Down Counter
Features
• Four Decade, Presettable Up-Down Counter with
Parallel Zero Detect
• Settable Register with Contents Continuously
Compared to Counter
• Directly Drives Multiplexed 7 Segment Common
Anode or Common Cathode LED Displays
• On-Board Multiplex Scan Oscillator
• Schmitt Trigger On Count Input
• TTL Compatible BCD I/O Port, Carry/Borrow, Equal,
and Zero Outputs
• Display Blank Control for Lower Power Operation;
Quiescent Power Dissipation <5mW
• All Terminals Fully Protected Against Static Discharge
• Single 5V Supply Operation
Description
The ICM7217 is a four digit, presettable up/down counter with
an onboard presettable register continuously compared to the
counter. The ICM7217 is intended for use in hard-wired
applications where thumbwheel switches are used for loading
data, and simple SPDT switches are used for chip control.
This circuit provides multiplexed 7 segment LED display
outputs, with common anode or common cathode
configurations available. Digit and segment drivers are
provided to directly drive displays of up to 0.8 inch
character height (common anode) at a 25% duty cycle. The
frequency of the onboard multiplex oscillator may be
controlled with a single capacitor, or the oscillator may be
allowed to free run. Leading zeros can be blanked. The
data appearing at the 7 segment and BCD outputs is
latched; the content of the counter is transferred into the
latches under external control by means of the Store pin.
The ICM7217 (common anode) and ICM7217A (common
cathode) versions are decade counters, providing a
maximum count of 9999, while the ICM7217B (common
anode) and ICM7217C (common cathode) are intended for
timing purposes, providing a maximum count of 5959.
This circuit provides 3 main outputs; a CARRY/BORROW
output, which allows for direct cascading of counters, a
ZERO output, which indicates when the count is zero, and
an
EQUAL output, which indicates when the count is equal
to the value contained in the register. Data is multiplexed to
and from the device by means of a three-state BCD I/O port.
The CARRY/BORROW,
EQUAL, ZERO outputs, and the
BCD port will each drive one standard TTL load.
To permit operation in noisy environments and to prevent
multiple triggering with slowly changing inputs, the count
input is provided with a Schmitt trigger.
Input frequency is guaranteed to 2MHz, although the device will
typically run with f
IN
as high as 5MHz. Counting and comparing
(EQUAL output) will typically run 750kHz maximum.
Ordering Information
PART
NUMBER
TEMP. RANGE
(
o
C) PACKAGE
DISPLAY DRIVER
TYPE
COUNT OPTION/
MAX COUNT PKG. NO.
ICM7217AIPI -25 to 85 28 Ld PDIP Common Cathode Decade/9999 E28.6
ICM7217CIPl -25 to 85 28 Ld PDIP Common Cathode Timing/5959 E28.6
ICM7217IJI -25 to 85 28 Ld CERDIP Common Anode Decade/9999 F28.6
lCM7217BlJl -25 to 85 28 Ld CERDIP Common Anode Timing/5959 F28.6
File Number 3167.1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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