CVBS Video Filter Amplifier with SmartSleep

and Bidirectional Video Support

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11

CVBS1

EXTCVBSIN

CVBSOUT1

CVBSIN

CVBSOUT2

GND

+3.3V

VDD

CLAMP

OFF

75

Ω

BUFFER

LOAD SENSE

6dB

75

Ω

LOAD SENSE

6dB

LPF

MAX9513

7

μA

NO VIDEO

SIGNAL

SHDN

INT/EXT

ACTIVE VIDEO

DETECT

SMARTSLEEP

CONTROL

LOGIC

+3.3V

+3.3V

OFF

OFF

OFF

OFF

OFF

OFF

CVBS2

CURRENT

DAC

Figure 2. Standby Mode

Standby Mode

In standby mode, the filter and output amplifiers are off,

and only the active video detect circuit is operational.

Quiescent current consumption is approximately 7µA

(Figure 2). The active video detect circuit checks

whether sync is present on the CVBSIN signal. If no

sync is detected, the device remains in standby mode.

Active-Detect Mode

The active video detect circuit slices the CVBSIN signal

at 4.7% of the power supply (155mV for a 3.3V supply).

If the transitions occur at a rate of 14.3kHz or higher, a

video signal is present. When the MAX9513 detects a

video signal with sync at the CVBSIN input, the control

logic enters the active-detect mode and enables the

load-sense circuitry (Figure 3). The supply current is

typically 17µA.

If an output load is not connected to any amplifier, the

MAX9513 remains in active-detect mode. Eight times per

second, each load-sense circuit checks for a load by

connecting an internal 15k

Ω pullup resistor to the output

for 1ms. If the output is pulled up, no load is present. If

the output stays low, a load is connected.