Rainbow Electronics MAX9508 - Manual (Page 10)

Detailed Description
In the typical application circuit for a portable DVD
player (Figure 1), the current DACs on a DVD decoder
chip generate video signals. When the internal signal
sources are selected, the MAX9508 filters those signals
and then drives the video connectors through a 75Ω
back termination resistor. When external video sources
are selected, the MAX9508 selects the external com-
posite video signal (EXTCVBSIN), filters, and amplifies
it. The output stages of the amplifiers connected to
COUT, YOUT, and CVBSOUT1 become high imped-
ance. 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
MAX9508
Video Filter Amplifier with SmartSleep and
Bidirectional Video Support
10 ______________________________________________________________________________________
75Ω
CURRENT
DAC
CURRENT
DAC
CURRENT
DAC
DVD CHIP
SVIDEO CHROMA
SVIDEO LUMA
TO Y/C SEPARATION
CVBS
CIN
YIN
EXTCVBSIN
COUT
YOUT
CVBSOUT1
INT/EXT
ACTIVE VIDEO
DETECT
CVBSIN
CVBSOUT2
LPF
CONTROL
LOGIC
MICROCONTROLLER
TO TFT LCD
TO TFT LCD
GND
+3.3V
0.1µF
V DD
CLAMP
BUFFER
LOAD SENSE
6dB
75Ω
75Ω
75Ω
LPF
BUFFER
LOAD SENSE
BUFFER
6dB
LOAD SENSE
6dB
75Ω
LOAD SENSE
6dB
75Ω
LPF
MAX9508
0.1µF
SHDN
SMARTSLEEP
+3.3V
Figure 1. Typical Application Circuit for Portable DVD Player