Two-Channel, Triple/Quad

RGB Video Switches and Buffers

______________________________________________________________________________________

15

__________Applications Information

Higher-Order RGB + Sync

Video Multiplexing

Higher-order RGB video multiplexers can be realized

by paralleling several MAX463/MAX464s. Connect LE

to V+ and use C

—

S

–

and E

—

N

–

to disable all devices but the

one in use. Since the disabled output resistance of the

MAX463/MAX464 is 250k

Ω, several devices may be

paralleled to form larger RGB video multiplexer arrays

without signal degradation. Connect series resistors at

each amplifier's output to isolate the disabled output

capacitance of each paralleled device, and use a

MAX469 or MAX470 to drive the output coaxial cables

(see Figure 7).

Paralleling MAX466s to Switch

1-of-4 RGB + Sync Signal Inputs

Figure 8 shows a 1-of-4 RGB + sync video mux/amp

circuit. The 1k

Ω disabled output resistance limits the

number of paralleled MAX465/MAX466s to no more

than two. The amplifier outputs are connected after a

22

Ω isolation resistor and ahead of a 50Ω back-termi-

nation resistor, which isolates the active amplifier out-

put from the capacitive load (5pF typ) presented by the

inactive output of the second MAX466. Impedance

mismatching is minimal, and the signal gain at the

cable end is near 1. This minimizes ringing in the out-

put signals. For multiplexing more than two devices,

see the section

Higher Order RGB + Sync Video

Multiplexing, above.

28

27

26

25

24

23

22

21

20

19

18

17

16

15

TOP VIEW

GND

IN1A

GND

IN2A

GND

IN3A

V-

IN0B

V-

IN1B

GND

IN2B

GND

IN3B

DIP/SO

1

2

3

4

5

6

7

8

9

10

11

12

13

14

IN0A

LE

EN

A0

CS

V-

OUT0

V-

OUT1

GND

V+

OUT2

V+

OUT3

MAX464

MAX466

IN0

GND

IN1

V-

V-

IN2

GND

IN3

DIP/SO

1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9

OUT0

GND

OUT1

V-

V-

OUT2

V+

OUT3

MAX468

MAX470

QUAD

BUFFERS

IN0

GND

IN1

V-

V-

IN2

GND

GND

DIP/SO

MAX467

MAX469

TRIPLE (RGB)

BUFFERS

1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9

OUT0

GND

OUT1

V-

V-

OUT2

V+

GND

_____________________________________________Pin Configurations (continued)