FMS6414 PRODUCT SPECIFICATION
REV. 1.0.1 6/27/02
3
Functional Description
Introduction
The FMS6414 is a monolithic continuous time video filter
designed for reconstructing the luminance, chrominance,
or composite video signals from D/A source. 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 Butterworth characteristic with an
optimization toward low over-shoot and flat group delay.
The video outputs are each 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 capacitors do not behave according
to the conventional RC time constant. Clamping for all
channels settles to less than 10mv within 5ms of a change in
video input source. In most applications the input coupling
capacitors are 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 inputs are 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
COUT
NC (Reserved)
VCC_VIDEO
8
7
6
5
FMS6414
SYNC STRIP,
REF, AND TIMING
gM
x2
x2
1V
gM
1V
YIN
YIN YOUT
YOUT
0.1µF
220µF
1µF
0.1µF
Video Cable
75Ω
75Ω
+5.0V
COUT
220µF
Video Cable
75Ω
75Ω
CIN
CIN
0.1µF
