SLR2016, SLO2016, SLG2016, SLY2016, SCD5584A
2006-01-23 5
Display Blanking
Blank the display by loading a blank or space into each digit of the
display or by using the (BL) display blank input. Setting the (BL)
input low does not affect the contents of data memory.
A flashing circuit can easily be constructed using a 555 as table
multivibrator. Figure 3 illustrates a circuit in which varying R1
(100K~10K) will have a flash rate of 1.0 Hz~10 Hz.
The display can be dimmed by pulse width modulating the (BL) at
a frequency sufficiently fast to not interfere with the internal clock.
The dimming signal frequency should be 2.5 kHz or higher. Dim-
ming the display also reduces power consumption.
An example of a simple dimming circuit using a 556 is illustrated in
Figure 4. Adjusting potentiometer R3 will dim the display by chang-
ing the blanking pulse duty cycle.
Flashing Circuit Using a 555 and Flashing
(Blanking) Timing
Dimming Circuit Using a 556 and Dimming
(Blanking) Timing
Typical Loading State Table
WR A1 A0 D6 D5 D4 D3 D2 D1 D0 Digit
3 2 1 0
H previously loaded display G R E Y
L L L H L L L H L H G R E E
L L H H L H L H L H G R U E
L H L H L L H H L L G L U E
L H H H L L L L H L B L U E
L L H H L L L H L H B L E E
L L L H L H L H H H B L E W
L X X see character code see char. set
IDCD5033
Timer
555
1
2
3
4
7
8
6
5
1
R
4.7 k
Ω
100 k
R
2
Ω
10 µF
C
3
0.01 µF
C
4
CC
V
= 5 V
To BL
Pin on
Display
IDCD5035
1
0
500 ms
Blanking Pulse Width
50% Duty Factor
2 Hz Blanking Frequency
~
~
~
~
~
~
IDCD5034
Dual Timer
556
1
2
3
4
13
14
12
11
500 k
R
3
Ω
1000 pF
C
3
CC
V
= 5 V
6
7
5
9
8
10
C
0.01 µF
4
0.01 µF
C
2
2
47 k
R
Ω
200
R
1
Ω
4700 pF
C
1
Control
Dimming (Blanking)
To BL Pin
on Display
IDCD5036
1
0
200 µs
Blanking Pulse Width
4 µs min., 196 µs max.
5 kHz Blanking Frequency
~
~
~
~
