MAX9597
Low-Power Audio/Video Interface
for Single SCART Connectors
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when the MAX9597 is operating without loads and with-
out any audio or video signals. Table 4 shows the qui-
escent power consumption in both operating modes.
Average power consumption is defined when the
MAX9597 drives typical signals into typical loads. Table 5
shows the average power consumption in full-power
mode, and Table 6 shows the input and output conditions.
Interfacing to an RF Modulator
If the set-top box modulates CVBS and mono audio
onto an RF carrier (for example, channel 3), a simple
application circuit can provide the needed signals (see
Figure 11). A 10kΩ resistor summer circuit between
TV_OUTR and TV_OUTL creates the mono audio sig-
nal. The resistor-divider to ground on TV_CVBS_OUT
creates a video signal with normal amplitude. The
unique feature of the MAX9597 that facilitates this
application circuit is that the audio and video output
amplifiers of the MAX9597 can drive multiple loads if
V
AUD
and V
VID
are both greater than 3.135V.
Floating-Chassis Discharge Protection
and ESD
Some set-top boxes have a floating chassis problem in
which the chassis is not connected to earth ground. As
a result, the chassis can charge up to 500V. When a
SCART cable is connected to the SCART connector,
the charged chassis can discharge through a signal
pin. The equivalent circuit is a 2200pF capacitor
charged to 311V connected through less than 0.1Ω to a
signal pin. The MAX9597 is soldered on the PCB when
it experiences such a discharge. Therefore, the current
spike flows through both external and internal ESD pro-
tection devices and is absorbed by the supply bypass
capacitors, which have high capacitance and low ESR.
