Rainbow Electronics MAX9508 - Manual (Page 13)

Full-Operation Mode
If a load is connected to an output, the corresponding
filter and amplifier turn on and remain on until the out-
put load is disconnected. In full-operation mode,
SmartSleep intelligently reduces the supply current
based on the input signal presence and output loading.
Figures 4, 5, and 6 show which portions of the
MAX9508 turn on and which remain off with different
load configurations.
When an amplifier is on, it continually checks if the load
has been disconnected by detecting if the amplifier
output is sourcing current during a horizontal line time.
If no sourcing current is detected within one horizontal
line time (approximately 64µs), the load has been dis-
connected and the amplifier returns to active-detect
mode. If, at any time, the input video signal is removed,
the MAX9508 returns to standby mode.
If the SmartSleep feature is not activated and the part is
not in shutdown, the filters and amplifiers completely
turn on, regardless of whether there is a video signal at
the CVBSIN input and whether there are loads connect-
ed at the outputs.
MAX9508
Video Filter Amplifier with SmartSleep and
Bidirectional Video Support
______________________________________________________________________________________ 13
CIN
YIN
EXTCVBSIN
COUT
YOUT
CVBSOUT1
CVBSIN
CVBSOUT2
LPF
GND
+3.3V
V DD
CLAMP
OFF
LOAD SENSE
6dB
75Ω
75Ω
LPF
BUFFER
LOAD SENSE
BUFFER
BUFFER
6dB
LOAD SENSE
6dB
75Ω
LOAD SENSE
6dB
75Ω
LPF
MAX9508
2.9mA QUIESCENT
SUPPLY CURRENT
PLUS
OUTPUT LOAD CURRENT
SVIDEO
CHROMA
SVIDEO
LUMA
CVBS1
75Ω
CURRENT
DAC
CURRENT
DAC
VIDEO SIGNAL
PRESENT
CURRENT
DAC
VIDEO ENCODER
SHDN
INT/EXT
ACTIVE VIDEO
DETECT
SMARTSLEEP CONTROL
LOGIC
+3.3V
+3.3V
0
TO
50mV
OFF
OFF
OFF
OFF
OFF
OFF
OFF
CVBS 2
Figure 4. Full-Operation Mode with CVBSOUT1 Loaded