ml6429 Fairchild Semiconductor, ml6429 Datasheet - Page 6

• Manufacturer Part Number: ml6429
• Description: Quad Video Cable Drivers Filters With Switchable Inputs
• Manufacturer: Fairchild Semiconductor

FUNCTIONAL DESCRIPTION
The ML6429 is a quad monolithic continuous time analog
video filter designed for reconstructing signals from four
video D/A sources. The ML6429 is intended for use in AC
coupled input and output applications.
The filters approximate a 4
characteristic with an optimization toward low overshoot
and flat group delay. All outputs are capable of driving
2V
of load capacitance at the output pin. Likewise, they are
capable of driving a 75Ω load at 1V
All channels are clamped during sync to establish the
appropriate output voltage swing range. Thus the input
coupling capacitors do not behave according to the
conventional RC time constant. Clamping for all channels
settles within 10ms of a change in video sources.
Input coupling capacitors of 0.1µF are reccommended for
all channels. During sync, a feedback error amplifier
sources/sinks current to restore the DC level. The net result
is that the average input current is zero. Any change in the
input coupling capacitors value will linearly affect the
clamp response times.
The RGB channels have no pulldown current sources and
are essentially tilt-free. The CV channel's inputs sink less
than 1µA during active video, resulting in a tilt of less than
1mV for a 220 µF. Up to 1000µF recommended to reude
tilt for TV applications.
SWAP MULTIPLEXER CONTROL
Output pins CV
independently selectable between three input sources
(CV
inputs SWAP CVF, SWAP CVU, and A/B MUX. This allows
the two outputs to remain independent and pass straight
through, to remain independent but swapped, or for both
outputs to have the same signal sourcing from either CV
or CV
to logic low, then CV
Y2, CV
Y
SWAP CVF is logic high, CV
CV
outputs from CV
and SWAP CVU will pull low if they are not driven.
The ML6429 is robust and stable under all stated load and
input conditions. Bypassing both V
ground ensures this performance. Two ML6429’s can be
connected in a master-slave sync configuration. When
using this configuration, only the “master” ML6429 is
required to have a signal with embedded sync present on
the CV
CV
“slave” IC will have its SYNC IN input connected to the
SYNC OUT output of the “master” ML6429.
6
OUT
P-P
INF
INU
INF,
A outputs video from the CV
INF
/Y1 input. If SWAP CVU is high, CV
into AC coupled 150Ω video loads, with up to 35pF
A or CV
INU
INU
and CV
A, CV
A, CV
B/Y3. If SWAP CVU is logic low, CV
INU
INU
INU
OUT
INU
INU
B input of the “slave” ML6429, the
B (See Table 1). If SWAP CVF is forced
A, CV
1/Y
B input. In the absence of sync on the
A/Y2 or CV
OUT2
OUT
INU
/Y
th
A and CV
B) depending on the digital
-order Butterworth
OUT
OUT2
INU
B sources from CV
/YOUTB outputs from
INU
B/Y3. Both SWAP CVF
CC
P-P
OUT
A, CV
pins directly to
.
2/Y
OUT1
INU
OUT
B input. If
/Y
OUT1
B are each
OUT
INU
/
A
A/
INF
SYNCIN AND SYNCOUT PINS
Each ML6429 has two sync detectors which control the
DC restore functions. The filtered channel has its own
detector, which controls the DC restore function during
the horizontal sync period of the CV
other sync detector controls the DC restore functions for
the filtered channels based upon the composite or luma
input at the CV
Required Setup: A composite or luma or green signal
must be present on CV
provide necessary sync signals to 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
CV
The SYNCOUT pin outputs a logic high when it detects
the horizontal sync of either the CV
input (note that one input is selected by the A/B MUX pin).
The SYNCIN pin is an input for an external H-sync logic
signal to enable or disable the internal DC restore loop for
the filtered channels. When SYNCIN is logic high, the DC
restore function is enabled.
For normal operation, the SYNCOUT pin is connected to
the SYNCIN pin (see Figure 4). If the CV
an embedded sync, an external sync can be applied on
the SYNCIN pin. In master-slave configurations, the
SYNCOUT of a ML6429 master can be used as the
SYNCIN of a ML6429 slave.
VIDEO I/O DESCRIPTION
Each input is driven by either a low impedance source or
the output of a 75Ω terminated line. The input is required
to be AC coupled via a 0.1µF coupling capacitor which
gives a nominal clamping time of 10ms. All outputs are
capable of driving an AC coupled 150Ω load at 2V
1V
load capacitance can be driven without stability or slew
issues. A 220µF AC coupling capacitor is recommended at
the output to reduce power consumption.
ANALOG MULTIPLEXER CONTROL
The four filter channels each have two input multiplexers
which are paired to select between two four-channel
video sources (i.e., composite video plus RGB component
video).
If A/B MUX is forced to logic high, it will select Bank<A>
of video inputs (CV
to be enabled. If A/B MUX is logic low, then Bank<B> of
video inputs (CV
be selected. If the A/B MUX is open, it will pull to logic
high.
P-P
INU
into a 75Ω load. At the output pin, up to 35pF of
B/Y3.
INU
INU
A/Y2 or CV
INU
B/Y3, R
A/Y2, R
INU
A/Y2 or CV
IN
B/Y5,G
INU
IN
A/Y4, G
B/Y3 pins.
INU
INF
IN
INU
B/Y7, B
A/Y2 or CV
/Y1 input. The
INU
INU
IN
B/Y3 inputs to
REV. 1.1 2/8/2001
A/Y6, B
does not have
A/Y2 or
IN
B/C2) will
IN
INU
P-P
A/C1)
B/Y3
or