ICM7228 Datasheet, PDF (16/17 Pages) Intersil Corporation – 8-Digit, Microprocessor- Compatible, LED Display Decoder Driver

ICM7228
V_DD
V_DD
1K
V_DD
1.4A_PEAK
2N6034
100Ω
SEGMENT
OUTPUT
ICM7228C/D
V_DD
DIGIT ^300Ω
OUTPUT
N
≈15Ω
1K _25Ω
(100mA_PEAK)
2N2219
1K
HIGH = HEX
LOW = SHUTDOWN
74C126 THREE-STATE BUFFER
PIN 9
HIGH = HEX OR SHUTDOWN
LOW = CODE B
HIGH = HEX
LOW = SHUTDOWN
HIGH = HEX OR SHUTDOWN
LOW = CODE B
HIGH = CODE B
LOW = HEX
CD4016
CD4066
CONTROL
CD4069 ^1N4148
PIN 9
PIN 9
HIGH = SHUTDOWN
LOW = CODE B
CD4069 ^1N4148
PIN 9
V_SS
V_SS
FIGURE 16. DRIVING HIGH CURRENT DISPLAY, COMMON
CATHODE ICM7228B/D TO COMMON CATHODE
DISPLAY
HIGH = SHUTDOWN
LOW = HEX
HIGH = SHUTDOWN
LOW = CODE B
CD4069
PIN 9
OPEN DRAIN OR OPEN
COLLECTOR OUTPUT
PIN 9
Three Level Input, ICM7228C and ICM7228D
As mentioned before, pin 9 is a three level input and controls
three functions: Hexadecimal display decoding, Code B dis-
play decoding and shutdown mode. In many applications, pin
9 will be left open or permanently wired to one state. When
pin 9 can not be permanently left in one state, the circuits illus-
trated in Figure 17 can be used to drive this three level input.
FIGURE 17. ICM7228C/D PIN 9 DRIVE CIRCUITS
Power Supply Bypassing
Connect a minimum of 47µF in parallel with 0.1µF capacitors
between V_DD and V_SS of ICM7228. These capacitors
should be placed in close proximity to the device to reduce
the power supply ripple caused by the multiplexed LED dis-
play drive current pulses.
Test Circuits
1
28
2
27
3
26
4
25
ID6 (HEXA/CODE B)
5
24
ID5 (DECODE)
6
23
ID7 (DATA COMING)
7
22
WRITE
8
ICM7228A
21
MODE
9
20
ID4 (SHUTDOWN)
10
19
ID1
11
18
ID0
12
17
ID2
13
16
ID3
V_DD
14
15
+
V_DD
f
d
5V
47µF
+0.1µF
g
-
V_SS
a
V_SS
c
D8 D7 D6 D5 D4 D3 D2 D1
e
COMMON ANODE DISPLAY
b
DP
FIGURE 18. FUNCTIONAL TEST CIRCUIT #1
9-32