lCM7217BlJl Intersil Corporation, lCM7217BlJl Datasheet - Page 12

• Manufacturer Part Number: lCM7217BlJl
• Description: 4-digit Led Display, Programmable Up/down Counter
• Manufacturer: Intersil Corporation

When using the circuit as a programmable divider (÷ by n
with equal outputs) a short time delay (about 1µs) is needed
from the EQUAL output to the RESET input to establish a
pulse of adequate duration. (See Figure 16).
When the circuit is configured to reload the counter or regis-
ter with a new value from the BCD lines (upon reaching
EQUAL), loading time will be digit “on” time multiplied by
four. If this load time is longer than one period of the input
count, a count can be lost. Since the circuit will retain data in
the register, the register need only be updated when a new
value is to be entered. RESET will not clear the register.
Test Circuit
THUMBWHEEL SWITCHES
COUNT INPUT
COMMON ANODE DISPLAY
BCD I/O 8s
BCD I/O 4s
BCD I/O 2s
BCD I/O 1s
+5V
V
DD
9999
D4
D3
D2
D1
e
f
LOAD REGISTER
LOAD COUNTER
d
g
a
D4
c
ICM7217
b
UP/DOWN
CARRY
EQUAL
ZERO
STORE
RESET
SCAN
12
e
f
N.O.
d
g
D3
a
10
11
12
13
14
1
2
3
4
5
6
7
8
9
c
b
EQUAL
N.O.
ICM7217B
V
V
ICM7217
DD
e
SS
FIGURE 16. EQUAL TO RESET DELAY
f
d
FIGURE 15. POWER ON RESET
g
a
D2
c
b
0.047µF
10Ω
33K
28
27
26
25
24
23
22
21
20
19
18
17
16
15
10kΩ
e
f
d
g
a
V
D1
DD
c
DISPLAY
CONTROL
b
47pF
5kΩ
RESET INPUT
d
g
c
e
ICM7217
a
b
f
V
V
RESET
DD
SS