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