Rainbow Electronics MAX9597 - Manual (Page 24)

MAX9597
Low-Power Audio/Video Interface
for Single SCART Connectors
24 ______________________________________________________________________________________
Stand-Alone Operational
Amplifier Applications
The input amplifier of the audio section can be utilized
for stand-alone operational amplifier applications by
configuring ENC_INR+ and ENC_INL+ input as the
noninverting input, ENC_INR- and ENC_INL- input as
the inverting input and ENC_INROUT and
ENC_INLOUT output as the output of the stand-alone
operational amplifier. The gain-bandwidth product of
the amplifier is 7MHz (typ).
Applications That Do Not Need
the Slow-Switch Signal
V
12
should be left unconnected if the MAX9597 is used
in an application that does not require the slow-
switch output signal. See Figure 18.
Power-Supply Bypassing
The MAX9597 features single 3.3V and 12V supply
operation and requires no negative supply. The 12V
supply V
12
is for the SCART slow-switching function.
For pin V 12 , place a 0.1μF bypass capacitor as close to
it as possible. Connect V AUD to 3.3V and bypass with a
10μF electrolytic capacitor in parallel with a 0.1μF
ceramic capacitor to audio ground. Bypass V
VID to
GND with a 0.1μF ceramic capacitor.
Using a Digital Supply
The MAX9597 was designed to operate from noisy digi-
tal supplies. The high video PSRR (47dB at 100kHz)
allows the MAX9597 to reject the noise from the digital
power supplies (see the
Typical Operating Character-
istics ). If the digital power supply is very noisy and
stripes appear on the television screen, increase the
supply bypass capacitance. An additional, smaller
capacitor in parallel with the main bypass capacitor
can reduce digital supply noise because the smaller
capacitor has lower equivalent series resistance (ESR)
and equivalent series inductance (ESL).
Layout and Grounding
For optimal performance, use controlled-impedance
traces for video signal paths and place input termina-
tion resistors and output back-termination resistors
close to the MAX9597. Avoid routing video traces par-
allel to high-speed data lines.
MAX9597
ENC_INL+
ENC_INL-
ENC_INLOUT
ENC_INR+
ENC_INR-
ENC_INROUT
STB CHIP
LEFT_P
LEFT_N
RIGHT_N
RIGHT_P
C1
R2
R1
R2
R2 C2
C1
R2
R1
R2 C2
R1
Figure 17. Differential to Single-Ended Conversion Circuit for Voltage Mode, Differential Audio Signals