MAX4397DCTM+ Maxim Integrated Products, MAX4397DCTM+ Datasheet - Page 12

• Manufacturer Part Number: MAX4397DCTM+
• Description: IC SW A/V SCART CON 48-TQFN
• Manufacturer: Maxim Integrated Products
• Type: Switchr

Specifications of MAX4397DCTM+

• 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 MAX4397DA/SA support 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
Audio/Video Switch for Dual SCART Connectors
Figure 2. Bidirectional SCART Pins
12
______________________________________________________________________________________
TV_R/C_IN
VIDEO INPUT
CLAMP/BIAS
CLAMP
MAX4397DA/SA
PULLDOWN
TV_R/C_OUT
N
Video Inputs
75Ω
2
C. See Tables
PIN 15
PIN 13
0.1µF
CONNECTORS
SCART
SCART
CABLE
pin as an input port, terminate the Red/Chroma output
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 MAX4397DA/SA
support S-video signals as an input from the VCR, the
MPEG decoder, and the TV, and also as a separately
switchable output to the TV and VCR. Because S-video
support 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 MAX4397DA/SA support Composite video (CVBS)
format, 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
separate input and output pins for the CVBS format.
0.1µF
PIN 15
PIN 13
75Ω
TV_R/C_OUT
N
MAX4397DA/SA
PULLDOWN
CLAMP/BIAS
CLAMP
VIDEO INPUT
TV_R/C_IN