MAX4397SCTM+T Maxim Integrated Products, MAX4397SCTM+T Datasheet - Page 12

• Manufacturer Part Number: MAX4397SCTM+T
• Description: IC SW A/V SCART CON 48-TQFN
• Manufacturer: Maxim Integrated Products
• Type: Switchr

Specifications of MAX4397SCTM+T

• Applications: DVD, Set-Top Boxes, TV
• Mounting Type: Surface Mount
• Package / Case: 48-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

All video inputs are AC-coupled with an external 0.1µF
capacitor. Either a clamp or bias circuit sets the DC
input level of the video signals. The clamp circuit posi-
tions the sync tip of the Composite (CVBS), the
Component RGB, or the S-Video Luma signal. If the sig-
nal does not have a sync tip, then the clamp positions
the minimum of the signal at the clamp voltage. The bias
circuitry is used to position the S-video Chroma signal at
midlevel of the Luma (Y) signal. On the video inputs that
can receive either a Chroma or a Red video signal, the
bias or clamp circuit is selected through I
3–12 for loading register details.
The MPEG decoder and VCR uses the RGB format and
fast switching to insert an on-screen display (OSD), usu-
ally text, onto the TV. The MAX4397 supports RGB as an
input from either the VCR or the MPEG decoder and as
an output only to the TV. The Red video signal of the
RGB format and the Chroma video signal of the S-VHS
format share the same SCART connector pin. Therefore,
RGB and S-video signals cannot be present at the same
time. Loop-through is possible with a Composite video
signal but not with RGB signals because the RGB
SCART pins are used for both input and output.
In SCART, there is the possibility of a bidirectional use
of the Red/Chroma pin. When using the Red/Chroma
pin as an input port, terminate the Red/Chroma output
Audio/Video Switch for Dual SCART Connectors
Figure 2. Bidirectional SCART Pins
12
______________________________________________________________________________________
TV_R/C_IN
VIDEO INPUT
CLAMP/BIAS
CLAMP
MAX4397
PULLDOWN
TV_R/C_OUT
N
75Ω
Video Inputs
2
C. See Tables
PIN 15
PIN 13
0.1µF
CONNECTORS
SCART
SCART
CABLE
with a 75Ω resistor to ground. Thus, a ground state is
provided by an active pulldown to GNDVID on the
Red/Chroma output to support the bidirectional Chroma
or Red I/O, turning the output source resistors into ter-
minations (see Figure 2). The active pulldown also pro-
vides the “Mute Output” function, and disables the
deselected video outputs. The “Mute Output” state is
the default power-on state for video.
For high-quality home video, the MPEG decoder, VCR,
and TV use the S-video format. The MAX4397 supports
S-video signals as an input from the VCR, the MPEG
decoder, and the TV, and also as a separately switch-
able output to the TV and VCR. Because S-video sup-
port was not included in the original specifications of
the SCART connector, the Luma (Y) signal of S-video
and the CVBS signal share the same SCART connector
pins. If S-video is present, then a Composite signal
must be created from the Y and C signals to drive the
RF_CVBS_OUT pin. For S-video, loop-through is not
possible since the Chroma SCART port is used for both
input and output.
The MAX4397 supports Composite video (CVBS) for-
mat, with inputs from the VCR, MPEG decoder, and TV.
Full loop-through is possible to the TV and VCR only,
since the MPEG decoder SCART connector has sepa-
rate input and output pins for the CVBS format.
0.1µF
PIN 15
PIN 13
75Ω
TV_R/C_OUT
N
PULLDOWN
MAX4397
CLAMP/BIAS
CLAMP
VIDEO INPUT
TV_R/C_IN