Rainbow Electronics MAX9512 - Manual (Page 10)

MAX9512
Video Filter Amplifier with SmartSleep
and Y/C Mixer Circuit
10 _ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ _
CVBS1
CIN
NO VIDEO
SIGNAL
YIN
COUT
YOUT
CVBSOUT1
CVBSOUT2
LPF
GND
+3.3V
V DD
LOAD SENSE
6dB
75 Ω
75 Ω
LPF
BUFFER
LOAD SENSE
BUFFER
6dB
LOAD SENSE
6dB
75 Ω
LOAD SENSE
6dB
75 Ω
MAX9512
7 µA
CHROMA
LUMA
CURRENT
DAC
CURRENT
DAC
VIDEO ENCODER
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
CVBS2
SHDN
ACTIVE VIDEO
DETECT
SMARTSLEEP
CONTROL
LOGIC +3.3V
Figure 2. Standby Mode Operation
Detailed Description
In the Typical Application Circuit (Figure 1), the current
DACs on a video encoder generate luma and chroma
video signals. The MAX9512 filters those signals and
then adds them together to create the composite video
signal. The output amplifiers drive the video connectors
through a 75Ω back termination resistor.
SmartSleep Feature
The SmartSleep feature is activated when the
SMARTSLEEP input is connected to logic high. The
SmartSleep feature provides intelligent power manage-
ment by selectively disabling the filters and output ampli-
fiers based on the presence of a luma video signal or
loads attached to the outputs. If the SmartSleep feature
is not activated and the part is not in shutdown, the filters
and output amplifiers completely turn on, regardless of
whether there is a video signal at the YIN input and
whether there are loads connected at the outputs.
SmartSleep only works with DC-coupled loads.
Standby Mode
In standby mode, the filters and output amplifiers are
off and only the active video detect circuit is active.
Quiescent current consumption is approximately 7µA
(Figure 2). The active video detect circuit checks if
sync is present on the YIN signal. If no sync is detected
the device remains in standby mode.