June, 2000

Datasheet

5

ML6415

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 150

Ω 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 75

Ω 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 150

Ω

load at 2VP-P, or 1VP-P into a 75

Ω 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.

FUNCTIONAL DESCRIPTION

CHROMINANCE (C) I/O

The chroma input is driven by a low impedance

source of 0.7Vp-p or the output of a 75

Ω 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 150

Ω load at 2VP-P,

or 1VP-P into a 75

Ω 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 600

Ω load

to 2VP-P, but is primarily intended to drive a modulator

load.