Detailed Description

In the typical application circuit shown in Figure 1, the

current DAC generates an internal video signal. When the

internal signal source is selected, the MAX9513 filters the

signal and then drives the video connectors through a

75

Ω back termination resistor. When the external video

source is selected, the MAX9513 selects the external

video signal (EXTCVBSIN), then clamps, filters, and

amplifies it. The output stage of the amplifier connected

to CVBSOUT1 becomes high impedance. The n-channel

switch at CVBSOUT1 turns on, thereby converting the

back termination resistor into an input termination resistor.

SmartSleep Feature

The SmartSleep feature is activated when the SMARTSLEEP

input is connected to logic-high. The SmartSleep feature

provides intelligent power management by selectively

disabling the filters and output amplifiers based on

the presence of video signals or loads attached to the

outputs. If the SmartSleep feature is not activated and

the part is not in shutdown, the filters and output ampli-

fiers completely turn on, regardless of whether there is

a video signal at the CVBSIN input and whether there

are loads connected at the outputs. SmartSleep only

works with DC-coupled loads.

CVBS Video Filter Amplifier with SmartSleep

and Bidirectional Video Support

10

______________________________________________________________________________________

CURRENT

DAC

DVD CHIP

TO Y/C SEPARATION

CVBSOUT/IN

EXTCVBSIN

CVBSOUT1

INT/EXT

ACTIVE VIDEO

DETECT

CVBSIN

CVBS SIGNAL

CVBSOUT2

CONTROL

LOGIC

MICROCONTROLLER

GND

+3.3V

0.1

μF

CLAMP

75

Ω

BUFFER

LOAD SENSE

6dB

75

Ω

LOAD SENSE

6dB

LPF

MAX9513

0.1

μF

SHDN

SMARTSLEEP

+3.3V

+3.3V

Figure 1. Typical Application Circuit for Portable DVD Player