Short-Circuit Protection

The MAX7481/MAX7482 typical application circuit

includes a 75

Ω back-termination resistor that limits short-

circuit current if an external short is applied to the video

output. The MAX7481/MAX7482 provide additional out-

put short-circuit protection to prevent damage in appli-

cations where amplifier output can be directly shorted.

Charge Pump and Linear Regulator

Portable video applications have space constraints that

limit the use of AC-coupling capacitors and power con-

straints that limit the use of batteries to generate the

negative supply rail. The MAX7481/MAX7482 simplify

and reduce space and power constraints by integrating

a charge pump and linear regulator to create a low-

noise negative supply from a single positive supply.

The charge pump inverts the positive supply to create

Bidirectional Video Filters/Buffers for Composite

and S-Video Portable Media Devices

_______________________________________________________________________________________

9

P/R

CVBSON

YCON

OUT3

(CVBS)

OUT1 (Y) AND

OUT2 (C)

OUT4

(Y, CVBS)

OUT5

(C)

IN3 AND IN4

(Y, C)

IN5

(CVBS)

IN1

(Y)

IN2

(C)

Low

Low

Low

Not Active

Not Active

GND

GND

Not Used

Not Used

Active

Active

Low

Low

High

Not Active

Active

GND

GND

Not Used

Not Used

Active

Active

Low

High

Low

Active

Not Active

GND

GND

Not Used

Not Used

Active

Active

Low

High

High

Active

Active

GND

GND

Not Used

Not Used

Active

Active

High

Low

Low

GND

GND

GND

GND

Not Used

Not Used

Not Used

Not Used

High

Low

High

GND

GND

Active

Active

Active

Not Used

Not Used

Not Used

High

High

Low

GND

GND

Active

GND

Not Used

Active

Not Used

Not Used

High

High

High

GND

GND

GND

GND

Not Used

Not Used

Not Used

Not Used

Table 1. Input/Output Truth Table

CVBSON

YCON

P/R = LOW

LPF

LPF

VIDEO

ADC

VIDEO

DAC

VIDEO

ADC

CONTROL

LOGIC

VIDEO

DAC

MAX7481

MAX7482

S4

S5

S1

S2

S3

75

Ω

0.1

μF

75

Ω

75

Ω

0.1

μF

0.1

μF

OUT2

OUT3

S8

S7

OUT1

IN3

IN5

IN4

IN2

IN1

S6

OUT5

OUT4

Figure 4. Signal Flow Diagram for Playback Mode