ML6426-1 FAIRCHILD [Fairchild Semiconductor], ML6426-1 Datasheet - Page 6

• Manufacturer Part Number: ML6426-1
• Description: High Bandwidth Triple Video Filters with Buffered Outputs for RGB or YUV
• Manufacturer: FAIRCHILD [Fairchild Semiconductor]

ML6426
Functional Description
The ML6426 is a triple monolithic continuous time video
filter designed for reconstructing video signals from an
YUV/RGB video D/A source. The ML6426 is intended for
use in AC coupled input and output applications.
The filters approximate a 4th-order Butterworth characteris-
tic with an optimization toward low overshoot and flat group
delay. All outputs are capable of driving 2V
coupled 150Ω video loads, with up to 35pF of load capaci-
tance. All outputs are capable of driving a 75Ω load at 1V
All channels are clamped during sync to establish the appro-
priate output voltage swing range (DC restore). Thus the
input coupling capacitors do not behave according to the
6
SYNC IN
R IN
G IN
B IN
0.1µF
0.1µF
0.1µF
16
2
5
6
7
8
9
1
R IN A/Y IN A
R IN B/Y IN B
G IN A/U IN A
G IN B/U IN B
B IN A/V IN A
B IN B/V IN B
A/B MUX
SYNCIN
MUX
MUX
MUX
ACTIVE HIGH
TRANSCONDUCTANCE
TRANSCONDUCTANCE
TRANSCONDUCTANCE
Figure 1. Typical Application Schematic
ERROR AMP
ERROR AMP
ERROR AMP
DISABLE
P-P
15
Figure 2. SYNC IN Pulse Width
into AC
PW MIN = 2µS
P-P
+
–
+
–
+
–
.
V CCO
12
5V
0.5V
0.5V
0.5V
conventional RC time constant. In most applications, the
ML6426's input coupling capacitors are only 0.1µF.
An external CMOS compatible HSYNC pulse is required
which is Active High on the SYNC IN Pin. See Figure 2.
During sync, the feedback clamp sources/sinks current to
restore the DC level. The net result is that the average input
current is zero. Any change in the input coupling capacitors'
value will linearly affect the clamp response times.
Each channel is essentially tilt-free. Each input is clamped
by a feedback amp which responds to the output during sync.
The ML6426 is robust and stable under all stated load and
input conditions. Bypassing both V
ground ensures this performance.
V CC
5V
V IH = 2.5V
V IL = 1.0V
4
4th-ORDER
4th-ORDER
4th-ORDER
FILTER A
FILTER B
FILTER C
50% x V SYNC IN
GNDO
14
×2
×2
×2
GND
3
G OUT /U OUT
R OUT /Y OUT
B OUT /V OUT
CC
13
11
10
220µF 75Ω
220µF 75Ω
220µF 75Ω
pins directly to
REV. 3A August 2004
DATA SHEET
B
G
R