FMS6413

REV. 1.0.2 6/27/02

3

Functional Description

Introduction

The FMS6413 is a monolithic continuous time video filter -

driver designed for reconstructing the video signals from a

D/A source. This chip is intended for use in applications

with AC coupled input and AC coupled outputs. (See

Figure 1) The reconstruction filter approximates a 4th-order

Butterworth characteristic with an optimization toward low

over-shoot and flat group delay. The video output is capable

of driving 2VP-P into an AC coupled 150

Ω video load, with

up to 35pF of load capacitance at the output pin. The channel

is clamped during sync to establish the appropriate output

voltage swing range. Thus the input coupling capacitor does

not behave according to the conventional RC time constant.

Clamping for the video channel settles to less than 10mv

within 5ms of a change in video input source. In most

applications the input coupling capacitor is 0.1µF. The input

typically sinks 1µA during active video, which nominally

tilts a horizontal line by about 2mV at the Video 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 time. This product is

robust and stable under all stated load and input conditions.

Capacitive bypassing VCC directly to ground ensures this

performance.

Video I/O

The video 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 video 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 220µF or larger AC

coupling capacitor.

Typical Applications Diagram

Figure 1.

1

NC (Reserved)

2

3

GND_VIDEO

4

NC (Reserved)

NC (Reserved)

NC (Reserved)

VCC_VIDEO

8

7

6

5

FMS6413

SYNC STRIP,

REF, AND TIMING

gM

x2

1V

VIDEO_IN

VIDEO_IN

VIDEO_OUT

VIDEO_OUT

0.1

µF

220

µF

1

µF

0.1

µF

Video Cable

75

Ω

75

Ω

+5.0V