ICM7217AIPI Intersil, ICM7217AIPI Datasheet - Page 9

• Manufacturer Part Number: ICM7217AIPI
• Description: 4 DIGIT UP/DOWN COUNTER 0-9999
• Manufacturer: Intersil
• Type: 4-Digit UP/Down Counterr

Specifications of ICM7217AIPI

• Rohs Status: RoHS non-compliant
• Count: 9999
• Frequency: 2MHz
• Voltage - Supply: 4.5 V ~ 5.5 V
• Current - Supply: 100mA
• Operating Temperature: -25°C ~ 85°C
• Package / Case: 28-DIP (0.600", 15.24mm)
• Other names: ICM7217AIPIIS

rising edge of the COUNT INPUT signal when UP/DOWN is
high. It is decremented when UP/DOWN is low. A Schmitt
trigger on the COUNT INPUT provides hysteresis to prevent
double triggering on slow rising edges and permits operation
in noisy environments. The COUNT INPUT is inhibited dur-
ing reset and load counter operations.
The STORE pin controls the internal latches and
consequently the signals appearing at the 7-Segment and
BCD outputs. Bringing the STORE pin low transfers the con-
tents of the counter into the latches.
The counter is asynchronously reset to 0000 by bringing the
RESET pin low. The circuit performs the reset operation by
forcing the BCD input lines to zero, and “presetting” all four
decades of counter in parallel. This affects register loading; if
LOAD REGISTER is activated when the RESET input is low,
the register will also be set to zero. The STORE, RESET and
UP/DOWN pins are provided with pullup resistors of approx-
imately 75kΩ.
BCD I/O Pins
The BCD I/O port provides a means of transferring data to
and from the device. The ICM7217 versions can multiplex
data into the counter or register via thumbwheel switches,
depending on inputs to the LOAD COUNTER or LOAD
REGISTER pins; (see below). When functioning as outputs,
the BCD I/O pins will drive one standard TTL load. Common
anode versions have internal pull down resistors and com-
mon cathode versions have internal pull up resistors on the
four BCD I/O lines when used as inputs.
LOADing the COUNTER and REGISTER
The BCD I/O pins, the LOAD COUNTER (LC), and LOAD
REGISTER (LR) pins combine to provide presetting and
compare functions. LC and LR are 3-level inputs, being self-
biased at approximately
both LC and LR open, the BCD I/O pins provide a multi-
plexed BCD output of the latch contents, scanned from MSD
to LSD by the display multiplex.
When either the LOAD COUNTER (Pin 12) or LOAD
REGISTER (Pin 11) is taken low, the drivers are turned off
and the BCD pins become high-impedance inputs. When LC
INPUT
INPUT A
INPUT B
INPUT
High
Low
FIGURE 11A. CMOS INVERTER
CD4069
1
/
2
V
1N4148
CD74HC03
DD
for normal operation. With
Disconnected
OUTPUT
OUTPUT
High
OUTPUT
ICM7217
9
is connected to V
els at the BCD pins are multiplexed into the counter. When
LR is connected to V
tiplexed into the register without disturbing the counter.
When both are connected to V
both register and counter will be loaded.
The LOAD COUNTER and LOAD REGISTER inputs are
edge-triggered, and pulsing them high for 500ns at room
temperature will initiate a full sequence of data entry cycle
operations (see Figure 3). When the circuit recognizes that
either or both of the LC or LR pins input is high, the multiplex
oscillator and counter are reset (to D4). The internal
oscillator is then disconnected from the SCAN pin and the
preset circuitry is enabled. The oscillator starts and runs with
a frequency determined by its internal capacitor, (which may
vary from chip to chip). When the chip finishes a full 4-digit
multiplex cycle (loading each digit from D4 to D3 to D2 to D1
in turn), it again samples the LOAD REGISTER and LOAD
COUNTER inputs. If either or both is still high, it repeats the
load cycle, if both are floating or low, the oscillator is
reconnected to the SCAN pin and the chip returns to normal
operation. Total load time is digit “on” time multiplied by 4. lf
the Digit outputs are used to strobe the BCD data into the
BCD I/O inputs, the input must be synchronized to the
appropriate digit (Figure 3). Input data must be valid at the
trailing edge of the digit output.
When LR is connected to GROUND, the oscillator is
inhibited, the BCD I/O pins go to the high impedance state,
and the segment and digit drivers are turned off. This allows
the display to be used for other purposes and minimizes
power consumption. In this display off condition, the circuit
will continue to count, and the CARRY/BORROW, EQUAL,
ZERO, UP/DOWN, RESET and STORE functions operate
as normal. When LC is connected to ground, the BCD I/O
pins are forced to the high impedance state without disturb-
ing the counter or register. See “Control Input Definitions”
(Table 2) for a list of the pins that function as three-state self-
biased inputs and their respective operations.
Note that the ICM7217 and ICM7217B have been designed
to drive common anode displays. The BCD inputs are high
true, as are the BCD outputs.
INPUT A
INPUT B
INPUT
INPUT
High
Low
FIGURE 11B. CMOS INVERTER
DD
CD4069
, the count input is inhibited and the lev-
DD
, the levels at the BCD pins are mul-
1N4148
CD4502B
DD
, the count is inhibited and
Disconnected
OUTPUT
High
OUTPUT
OUTPUT