ML6415
FUNCTIONAL DESCRIPTION
INTRODUCTION
This product is a dual monolithic continuous time video
filter designed for reconstructing the luminance and chro-
minance signals from an S-Video D/A source. Composite
video output is generated by summing the Y and C out-
puts. The chip is intended for use in applications with AC
coupled input and AC coupled outputs. (See Figure 1)
The reconstruction filters approximate a 4th-order But-
terworth characteristic with an optimization toward low
overshoot and flat group delay. Y, C, and CV outputs are
capable of driving 2VP-P into AC coupled 150Ω video
loads, with up to 35pF of load capacitance at the output
pin.
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 con-
ventional RC time constant. Clamping for all channels
settles to less than 10mv within 5ms of a change in video
input sources.
In most applications the input coupling capacitors are
0.1µF. The Y and C input typically sinks 1µA during active
video, which nominally tilts a horizontal line by about
2mV at the Y output. During sync, the clamp typically
sources 20µA to restore the DC level. The net result is that
the average input current is zero.
Any change in the input coupling capacitor’s value will
inversely alter the amount of tilt per line. Such a change
will also linearly affect the clamp response times.
This product is robust and stable under all stated load
and input conditions. Capacitive bypassing VCC directly to
ground ensures this performance.
LUMINANCE (Y) I/O
The luma input is driven by either a low impedance source
of 1Vp-p or the output of a 75Ω terminated line. The
input is required to be AC coupled via a 0.1µF coupling
capacitor which allows for a settling time of 5ms. The
luma output is capable of driving an AC coupled 150Ω
load at 2VP-P, or 1VP-P into a 75Ω load. Up to 35pF of
load capacitance (at the output pin) can be driven without
stability or slew issues. The output is AC coupled with a
400µF or larger AC coupling capacitor.
CHROMINANCE (C) I/O
The chroma input is driven by a low impedance
source of 0.7Vp-p or the output of a 75Ω terminated
line. The input is required to be AC coupled via a
0.1µF coupling capacitor which allows for a clamp
setting time of 5ms. The chroma output is capable
of driving an AC coupled 150Ω load at 2VP-P,
or 1VP-P into a 75Ω load. Up to 35pF of load
capacitance can be driven without stability or slew issues.
A 0.1µF AC coupling capacitor is recommended at the
output. (This reduces the circuit cost as chroma does not
contain low frequency components.)
COMPOSITE VIDEO (CV) OUTPUT
The composite video output is capable of driving 2 loads
to 2VP-P. It is intended to drive a TV and a VCR. Either
the TV input or the VCR input can be shorted to ground
and the other output will still meet specifications. Up to
35pF of load capacitance (at the output pin) can be driven
without stability or slew issues.
RF MODULATOR OUTPUT
The RF modulator output is capable of driving a 600Ω load
to 2VP-P, but is primarily intended to drive a modulator
load.
June, 2000
Datasheet
5
MICRO-LINEAR [ MICRO LINEAR CORPORATION ]
