FIGURE 6.
Driving a small LED Display
(Typically 1/8") at 12V power
supply. The 2.7kWresistors
provide approximately 3 mA
segment drive.
10kW(typical)
2.5kW
(typical)
7 SEGMENT
OUTPUT
DIGITAL SELECT OUTPUTS
LS7055/LS7056
THUMBWHEEL
SWITCHES
7 SEGMENT
OUTPUTS
BCD
OUTPUTS
DIGIT SELECT
OUTPUTS
24 25 26 27 28 29 30
32 33 34 35
17
18
19
20 21
22
BCD TO 7
SEGMENT
DECODER
LAMP TEST INPUT
(OPTIONAL-LS7056)
MULTIPLEXER
BLANKING
OVERRIDE
DIGIT SELECT
GENERATOR
SCAN INPUT CLOCK
BLANKING
GENERATOR
31
SCAN
OSCILLATOR
INPUT
MAINSIGNAL
OUTPUT
9
LATCH
DATA TRANSFER INPUT
B1
PRESIGNAL
OUTPUT
10
36
B4
11
BCD
DATA
INPUTS
B2
12
MAINSIGNAL STORE
ZERO DETECT
OUTPUT
38
5
B8
13
MAINSIGNAL COMPARATOR
DIVIDE
CONTROL INPUT 1
2
INHIBIT
INTERNAL
RESET INPUT
DIVIDE
CONTROL INPUT 2
3
PRESIGNAL STORE
PRESIGNAL COMPARATOR
COUNT
INPUT
RESET
INPUT
+1, 5, 6
SELECT
4
6
40
ZERO DETECTOR
COUNT INHIBIT
INPUT
COUNTER RESET
1
INHIBIT
INTERNAL
PRESET INPUT
COUNT
6 DECADE UP/DOWN COUNTER
STORAGE
SELECT 1
COUNTER PRESET
MAINSIGNAL STORE
PRESET ENABL
INPUT
UP/DOWN
INPUT
7
15
PRESIGNAL STORE
PRESET STORE
UP/DOWN
CONTROL
DECODER
PRESET STORE
39
16
STORAGE
SELECT 2
FIGURE 7. LS7055/LS7056 BLOCK DIAGRAM
7055-012703-6
LSI [ LSI COMPUTER SYSTEMS ]
