ML6421CS-4 MICRO-LINEAR [Micro Linear Corporation], ML6421CS-4 Datasheet - Page 8

• Manufacturer Part Number: ML6421CS-4
• Description: Triple Phase and Sinx/x Equalized, Low-Pass Video Filter
• Manufacturer: MICRO-LINEAR [Micro Linear Corporation]

ML6421
FUNCTIONAL DESCRIPTION
The ML6421 single-chip Triple Video Filter IC is intended
for consumer and low cost professional video
applications. Each of the three channels incorporates an
input buffer amplifier, a sixth order lowpass filter, a first
order allpass equalizer, Sinx/x equalizer and an output
amplifier capable of driving 75
The ML6421 can be driven by a DAC with Range down to
0V. When Range is low the input and output signal range
is 0.5V to 2.5V. When the input signal includes 0V, Range
should be tied high. In this case, an offset is added to the
input so that the output swing is kept between 0.5V to
2.5V. The output amplifier is capable of driving up to
24mA of peak current; therefore the output voltage should
not exceed 1.8V when driving 75 to ground.
8
OUTC
+5V
INC
INPUT SIGNAL = 2V
0.1 F
0.001 F
100 F
P-P
75
85
DECOUPLING
0.1 F
FB2
INPUT
INPUT
TERMINATION
FB1
100 F
to ground.
Figure 9. ML6421 AC Coupled DC Bias Test Circuit
BIAS
DC
SUPPLY NOISE
CLAMPING
47
3.1k
1k
0.1 F
0.1 F
0.1 F
1 F
1nF
1nF
1nF
1
2
3
4
5
6
7
8
GNDB
V
GND
GNDC
V
V
V
V
IN
CC
CC
OUT
CC
C
C
B
C
APPLICATION GUIDELINES
OUTPUT CONSIDERATIONS
The triple filters have unity gain. The circuit has unity
gain (0dB) when connected to a 150
gain when driving a 75
resistor. The output may be either AC or DC coupled. For
AC coupling, the –3dB point should be 5Hz or less. There
must also be a DC path of -500 to ground for output
biasing.
INPUT CONSIDERATIONS
The input resistance is 4k . The input may be either DC or
AC coupled. (Note that each input sources 80 to 125µA of
bias current). The ML6421 is designed to be directly
driven by a DAC. For current output video DACs, a 75
150 resistor to ground may need to be added to the DAC
output (filter input).
RANGE
V
V
GNDA
V
OUT
OUT
V
GND
V
CC
IN
IN
A
A
A
B
B
3.1k
47
16
15
14
13
12
11
10
9
1nF
1k
0.1 F
1 F
load via a 75
100 F
0.1 F
75
75
100 F
0.1 F
load, and a –6dB
85
series output
3.1k
47
INB
1k
85
INA
OUTA
OUTB
1 F
or