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

Ω

10 µF

0.01 µF

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

Ω

1000 pF

CC

V

= 5 V

6

7

5

9

8

10

C

0.01 µF

4

0.01 µF

2

47 k

R

Ω

200

Ω

4700 pF

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

~

~

~

~