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ML6426CS15X

High Bandwidth Triple Video Filters with Buffered Outputs for RGB or YUV

Fairchild Semiconductor 

ML6426

DATA SHEET

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 2VP-P into AC

coupled 150Ω video loads, with up to 35pF of load capaci-

tance. All outputs are capable of driving a 75Ω load at 1VP-P.

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

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 VCC pins directly to

ground ensures this performance.

RINA/YINA

2

RIN

0.1µF RINB/YINB

5

GINA/UINA

6

GIN

0.1µF GINB/UINB

7

BINA/VINA

8

BIN

0.1µF BINB/VINB

9

A/B MUX

1

SYNCIN

SYNC IN 16

MUX

MUX

TRANSCONDUCTANCE

ERROR AMP

TRANSCONDUCTANCE

ERROR AMP

MUX

TRANSCONDUCTANCE

ERROR AMP

ACTIVE HIGH

DISABLE

15

5V

12

VCCO

5V

4

VCC

0.5V

0.5V

0.5V

4th-ORDER

FILTER A

4th-ORDER

FILTER B

4th-ORDER

FILTER C

ROUT/YOUT 220µF 75Ω

R

×2

13

GOUT/UOUT 220µF 75Ω

G

×2

11

BOUT/VOUT 220µF 75Ω

B

×2

10

GNDO

14

GND

3

Figure 1. Typical Application Schematic

VIH = 2.5V

VIL = 1.0V

50% x VSYNC IN

PWMIN = 2µS

Figure 2. SYNC IN Pulse Width

6

REV. 3A August 2004

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