MAX4397DCTM+T Maxim Integrated Products, MAX4397DCTM+T Datasheet - Page 13

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

Specifications of MAX4397DCTM+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

The DC level at the video outputs is controlled so that
coupling capacitors are not required, and all of the video
outputs are capable of driving a DC-coupled, 150Ω,
back-terminated coax load with respect to ground.
In a typical television input circuit (see Figure 3), the
video output driver on the SCART chip only needs to
source current. Users should note that, while the
SCART specification states 75Ω impedance, in prac-
tice, typical SCART chip implementations assume 75Ω
input resistance to ground (and source current from the
video output stage).
Since some televisions and VCRs use the horizontal
sync height for automatic gain control, the
MAX4397DA/SA accurately reproduce the sync height
to within ±2%.
The MAX4397DA/SA support the IEC 933-1,
Amendment 1, tri-level slow switching that selects the
aspect ratio for the display (TV). Under I
control, the MAX4397DA/SA set the slow-switching out-
put voltage level. Table 1 shows the valid input levels of
the slow-switching signal and the corresponding oper-
ating modes of the display device.
Two bidirectional ports are available for slow-switching
signals for the TV and VCR. The slow-switching input
status is continuously read and stored in the register
0Eh. The slow-switching outputs can be set to a logic
level or high impedance by writing to registers 07h and
09h. See Tables 8 and 10 for details.
The VCR or MPEG decoder outputs a fast-switching
signal to the display device or TV to insert an on-screen
display (OSD). The fast-switching signal can also be
Figure 3. Typical TV Input Circuit
Audio/Video Switch for Dual SCART Connectors
MAX4397DA/SA
5kΩ
SET-TOP BOX
+5V
OUTPUT
VIDEO
______________________________________________________________________________________
TERMINATION
RESISTOR
BACK
75Ω
SCART
CABLE
Slow Switching
Fast Switching
Video Outputs
75Ω
INPUT
TERMINATION
RESISTOR
2
0.1µF
C-compatible
TV
RESTORE
DC
set to a constant high or low output signal through the
I
through writing to register 07h.
The MAX4397DA/SA include an on-chip mixer to pro-
duce Composite video (CVBS) when S-video (Y and C)
is present. The Composite video drives the
RF_CVBS_OUT output pin. The circuit sums Y and C
signals to obtain the CVBS component. A +6dB output
buffer drives RF_CVBS_OUT.
The encoder DAC outputs need to be lowpass-filtered
to reject the out-of-band noise. The MAX4397DA/SA
integrate the reconstruction filter. The filter is fourth
order, which is composed of two Sallen-Key biquad in
cascade, implementing a Butterworth-type transfer
function. The internal reconstruction filters feature a
5.5MHz cutoff frequency and -30dB minimum attenua-
tion at 27MHz. Note that the SET pin is used to set the
accuracy of the filter cutoff frequency. Connect a
100kΩ resistor from SET to ground.
All audio inputs for the MAX4397SA are single-ended
and AC-coupled. The MAX4397DA audio inputs are
singled-ended and AC-coupled except for the audio
encoder input, which is differential DC-coupled.
The audio block has three stereo audio inputs from the
TV, the VCR, and the MPEG decoder SCART. Each
input has a 100kΩ resistor connected to an internally
generated voltage equal to 0.23 x V
encoder input of the MAX4397DA, where the DC bias is
fixed externally.
Table 1. Slow-Switching Modes
2
SLOW-SWITCHING
SIGNAL VOLTAGE
C interface. The fast-switching output can be set
9.5 to 12.6
4.5 to 7.0
0 to 2
(V)
Video Reconstruction Filter
Display device uses an internal source
such as a built-in tuner to provide a
video signal
Display device uses a video signal from
the SCART connector and sets the
display to a 16:9 aspect ratio
Display device uses a signal from the
SCART connector and sets the display
to a 4:3 aspect ratio
SCART Audio Switching
MODE
12
, except for the
Audio Inputs
Y/C Mixer
13