ML6427CS Fairchild Semiconductor, ML6427CS Datasheet - Page 8
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ML6427CS
Manufacturer Part Number
ML6427CS
Description
Video ICs Cable Driver/Filter 75Ohm Quad Video
Manufacturer
Fairchild Semiconductor
Type
Provide DC coupled outputs for certain applicationsr
Specifications of ML6427CS
Operating Supply Voltage
5 V
Maximum Operating Temperature
70 C
Package / Case
SOIC-24
Minimum Operating Temperature
0 C
Mounting Style
SMD/SMT
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Other names
ML6427CS_NL
Available stocks
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Part Number
Manufacturer
Quantity
Price
Part Number:
ML6427CS
Manufacturer:
ML
Quantity:
20 000
ML6427
TYPICAL APPLICATIONS
BASIC APPLICATIONS
The ML6427 provides channels for two banks of inputs for
RGB and composite video. The R and G channels can be
used as luma inputs while the B channel can be used as a
chroma input. Composite outputs and an H-sync output
are also provided. There are several configurations
available with the ML6427. Figure 4 includes a list of
basic output options for composite, S-video, TV modulator,
and RGB outputs. Note that each composite channel can
drive a CV load and a channel modulator simultaneously.
The ML6427 standalone can be used as an EVC or SCART
cable driver with nine video sources (75W or low
impedance buffer) and seven video outputs. All inputs and
outputs are AC coupled. When driving seven loads the
power dissipation must be calculated to ensure that the
junction temperature doesn't exceed 120ºC.
EVC CABLE DRIVING
The ML6427 can be configured to drive composite video,
S-video, and horizontal sync through an EVC connector
(Figure 5). Composite video and S-video inputs are filtered
through 4
internal 75W cable drivers. A buffered H-sync output is
also available.
SCART CABLE DRIVING
The ML6427 can be configured either as a SCART cable
driver (Figure 4) or as a SCART cable driver and S-video
driver (Figure 6). A horizontal sync output is also available.
Note that the ML6427 can be used in a master-slave mode
where the SYNCOUT signal from the master is used as the
SYNCIN signal of the slave. This allows the CV, S-video,
and RGB channels to operate under the same sync signals.
Note that in SCART applications it is not always necessary
to AC couple the outputs. Systems using SCART
connectors for RGB and composite video can typically
handle between 0 and 2VDC offset (see DC Coupled
Applications section).
RGB APPLICATIONS
RGB video can be filtered and driven through the ML6427
in one of two ways:
1. For sync suppressed RGB the sync signal can be derived
from the composite or luma signal on the inputs of
CV
2. For RGB with sync on the green signal the green
channel must be fed into either the CV
Y3 input. The sync will be extracted from green and used
on red and bue channels. See also the SYNCIN and
SYNCOUT Sections.
8
INF
A/Y2 or CV
th
-order Butterworth filters and driven through
INF
B/Y3.
INF
A/Y2 or CV
INF
B/
OSD (ON-SCREEN DISPLAY) APPLICATIONS
Unfiltered RGB video from an OSD processor needs to be
filtered and then synchronized to a fast blanking interval
or alpha-key signal for later video processing. With the
total filter delay being 80ns ±10ns a D flip-flop or similar
delay element can be used to delay the fast blanking
interval or alpha-key signal. This will synchronize the RGB
and OSD signals (Figure 9).
CCIR656 AND CCIR601 APPLICATIONS
Composite or luma channels can be fed back into an
alternate channel or into another ML6427 (master-slave
configuration) so that approximately 80dB/decade
attenuation outputs are provided. The ML6427 can be
configured for composite and luma loopback (Figure 7).
H-sync outputs are also provided.
CHANNEL MULTIPLEXING
The ML6427 can be configured for multiple composite
channel multiplexing (Figure 8). Composite sources such
as VCRs, video game consoles, and camcorders can be
selected using the ML6427 swap mux controls. A/B MUX,
SWAP CVU, and SWAP CVF signals can be used to select
and route from various input sources.
DC COUPLED APPLICATIONS
A 220µF capacitor coupled with a 150W termination
resistor forms a highpass filter which blocks DC while
passing the video frequencies and avoiding tilt. Lower
value capacitors, such as 10µF, would create a problem.
By AC coupling the average DC level is zero.
Consequently the output voltages of all channels will be
centered around zero.
Alternately, DC coupling the output of the ML6427 is
allowable. There are several tradeoffs: The average DC
level on the outputs will be 2V; Each output will dissipate
an additional 40mW nominally; The application will need
to accommodate a 1VDC offset sync tip; and it is
recommended to use only one 75W load per output.
However, if it is necessary to drive two loads at a time on
the composite output while DC coupling is used then the
swap–mux and 5
the filtered composite signal on both the 4
drivers. This divides the composite load driving
requirement into two line drivers versus one.
Required Setup: A composite or luma or green signal must
be present on the CV
provide necessary sync signals to the other channels (R, G,
B, Y, C). Otherwise, sync must be provided at the SYNCIN
pin. For RGB applications, the green channel with sync
can be used as an input to CV
th
line driver can be configured to enable
INF
A/Y2 or the CV
INF
A/Y2 or CV
INF
B/Y3 input to
th
INF
and 5
B/Y3.
th
line