ML6428

S-Video Filter and 75

W Line Drivers with

Summed Composite Output

GENERAL DESCRIPTION

The ML6428 is a dual Y/C 4th-order Butterworth lowpass
video filter optimized for minimum overshoot and flat
group delay. The device also contains a summing circuit
to generate filtered composite video.

The Y and C input signals from DACs are AC coupled into
the ML6428. Both channels have DC restore circuitry to
clamp the DC input levels during video sync. The Y
channel uses a sync tip clamp. The CV and the C
channels share a feedback clamp.

All outputs must be AC coupled into their loads for the -1
and -3 versions. The -2 and -4 versions are DC coupled.
All inputs (-1, -2, -3 and -4 versions) are AC coupled. The
Y or C outputs can drive 2VP-P into a 150

W load, while

the CV output can drive 2VP-P into 75

W. Thus the CV

output is capable of driving two independent 150

W loads

to 2VP-P.

On the CV output, one of the 75

W loads can be shorted to

ground with no loss of drive to the remaining load. The Y,
C and CV channels have a gain of 2 (6dB) with 1VP-P
input levels.

BLOCK DIAGRAM

FEATURES

6.7MHz Y and C filters, with CV out for NTSC or PAL

W cable line driver for Y, C, CV, and TV modulator

43dB stopband attenuation at 27MHz

1dB flatness up to 4.8MHz

No external frequency select components or clocks

12ns group delay flatness up to 10MHz

5% overshoot on any input edge

AC coupled input and output (ML6428CS-1 and -3)

AC coupled input and DC coupled output
(ML6428CS-2 and -4)

0.4% differential gain on all channels, 0.4º differential
phase on all channels

0.7% total harmonic distortion on all channels

5V ±10% operation

DC restore with low tilt

BUFFER

TRANSCONDUCTANCE
ERROR AMP

BUFFER

SYNC TIP CLAMP

4th-ORDER

FILTER

4th-ORDER

FILTER

GND

CIN

YIN

YOUT

CVOUT

COUT

VCCO

VCC

DATASHEET June, 2000

ML6428

DATASHEET June, 2000

Micro Linear makes no representations or warranties with respect to the accuracy, utility, or completeness of the contents
of this publication and reserves the right to make changes to specifications and product descriptions at any time without
notice. No license, express or implied, by estoppel or otherwise, to any patents or other intellectual property rights is granted
by this document. The circuits contained in this document are offered as possible applications only. Particular uses or
applications may invalidate some of the specifications and/or product descriptions contained herein. The customer is urged
to perform its own engineering review before deciding on a particular application. Micro Linear assumes no liability
whatsoever, and disclaims any express or implied warranty, relating to sale and/or use of Micro Linear products including
liability or warranties relating to merchantability, fitness for a particular purpose, or infringement of any intellectual property
right. Micro Linear products are not designed for use in medical, life saving, or life sustaining applications.

© Micro Linear 2000. is a registered trademark of Micro Linear Corporation. All other trademarks are the property of their
respective owners.

Products described herein may be covered by one or more of the following U.S. patents: 4,897,611; 4,964,026; 5,027,116;
5,281,862; 5,283,483; 5,418,502; 5,508,570; 5,510,727; 5,523,940; 5,546,017; 5,559,470; 5,565,761; 5,592,128; 5,594,376;
5,652,479; 5,661,427; 5,663,874; 5,672,959; 5,689,167; 5,714,897; 5,717,798; 5,742,151; 5,747,977; 5,754,012; 5,757,174;
5,767,653; 5,777,514; 5,793,168; 5,798,635; 5,804,950; 5,808,455; 5,811,999; 5,818,207; 5,818,669; 5,825,165; 5,825,223;
5,838,723; 5.844,378; 5,844,941. Japan: 2,598,946; 2,619,299; 2,704,176; 2,821,714. Other patents are pending.

TABLE OF CONTENTS

WARRANTY

General Description ................................................................................................................................................... 1
Features ...................................................................................................................................................................... 1
Block Diagram ........................................................................................................................................................... 1
Pin Configuration ....................................................................................................................................................... 3
Pin Descriptions ......................................................................................................................................................... 3
Absolute Maximum Ratings ........................................................................................................................................ 4
Operating Conditions ................................................................................................................................................. 4
Electrical Characteristics ..................................................................................................... ....................................... 4
Functional Description ............................................................................................................................................... 6
Performance Data ....................................................................................................................................................... 7
Typical Applications ................................................................................................................................................... 8
Physical Dimensions .................................................................................................................................................. 11
Ordering Information .................................................................................................................................................. 11

ML6428

DATASHEET June, 2000

ELECTRICAL TABLE

Unless otherwise specified, VCC = 5V ±10%, All inputs AC coupled with 100nF, TA = Operating Temperature Range (Note 1)

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

ICC

Supply Current

No Load (VCC = 5.0V)

Low Frequency Gain (All Channels)

VIN = 100mVP-P at 300KHz

5.34

6.0

6.65

C DC Output Level (During Sync)

Sync Present on Y

1.7

1.9

2.3

Y Sync Output Level

ML6428-1

Sync Present on Y

0.7

0.9

1.3

ML6428-3

ML6428-2

Sync Present on Y

0.35

0.54

0.95

ML6428-4

Y+C Sync Output Level

ML6428-1

Sync Present on Y

0.7

0.92

1.3

ML6428-3

ML6428-2

Sync Present on Y

0.35

0.48

0.95

ML6428-4

tCLAMP

Clamp Response Time (Y Channel)

Settled to Within 10mV

f1dB

-1dB Bandwidth (Flatness) (All Channels)

4.0

4.8

MHz

-3dB Bandwidth (Flatness) (All Channels)

6.7

MHz

0.8fC

0.8 x fC Attenuation (Y, C)

1.5

fSB

Stopband Rejection (All Channels)

fIN = 27MHz to 100MHz worst case

Input Signal Dynamic Range (All Channels) AC Coupled

ML6428-1, -2

1.0

1.4

VP-P

ML6428-3, -4

1.2

1.4

VP-P

NOISE

Output Noise (All Channels)

25Hz to 50MHz

2.3

mVRMS

Peak Overshoot (All Channels)

2VP-P Output Pulse (loaded)

4.3

ISC

Output Short Circuit Current (All Channels) VOUT C, Y, or CV (Note 2)

100

Output Shunt Capacitance (All Channels)

All Outputs

Differential Gain (All Channels)

All Outputs

0.4

Differential Phase (All Channels)

All Outputs

0.4

THD

Output Distortion (All Channels)

VOUT = 1.8VP-P,

0.7

Y/C Out at 3.58MHz/4.43MHz

ABSOLUTE MAXIMUM RATINGS

Absolute maximum ratings are those values beyond which
the device could be permanently damaged. Absolute
maximum ratings are stress ratings only and functional
device operation is not implied.

DC Supply Voltage ........................................ -0.3V to 7V
Analog & Digital I/O ............ GND 0.3V to VCC + 0.3V
Output Current (Continuous)

CV Channel ........................................................ 60mA
C and Y Channels ................................................ 30mA

Junction Temperature .............................................. 150°C
Storage Temperature Range ..................... 65°C to 150°C
Lead Temperature (Soldering, 10 sec) ..................... 260°C
Thermal Resistance (

qJA) ..................................... 67°C/W

OPERATING CONDITIONS

Temperature Range ....................................... 0°C to 70°C
VCC Range ..................................................4.5V to 5.5V

ELECTRICAL CHARACTERISTICS

ML6428

DATASHEET June, 2000

The ML6428 is a dual monolithic continuous time video
filter designed for reconstructing the luminance and
chrominance signals from an S-Video D/A source.
Composite video output is generated by summing the Y
and C outputs. The ML6428 is intended for use in AC
coupled input and output applications. The ML6428CS-2,
-4 is intended for AC coupled input and DC coupled
output applications (see Figures 5 and 6).

The filters have a 4th-order Butterworth characteristic with
an optimization toward low overshoot and flat group
delay. All outputs are capable of driving 2VP-P into AC
coupled 150

W video loads, with up to 35pF of load

capacitance at the output pin. The CV output can drive
two video loads plus a high-impedance modulator. Thus
the CV output is intended to simultaneously drive a VCR,
a TV, and a high-impedance modulator. Y and C are
capable of driving a 75

W load at 1VP-P. The ML6428 is

capable of driving two composite loads and a TV
modulator simultaneously.

All channels are 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 within 2ms of a change in video input
sources.

In most applications, the ML6428's input coupling
capacitors are 0.1µF. The Y input sinks 1.6µA during
active video, which nominally tilts a horizontal line by
2mV (max) at the Y output (Figure 4). 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 times.

The C channel has no pulldown current sources and is
essentially tilt-free. Its input is clamped by a feedback
amp which responds to the CV output. Since CV = Y+C,
the CV output will droop by the same amount as Y during
active video, and will rise by the same amount as Y
during sync.

The ML6428 is robust and stable under all stated load and
input conditions. Capacitavely bypassing both VCC pins
directly to ground ensures this performance. (See Figures
5 and 6)

LUMINANCE (Y) I/O

The luma input is driven by either a low impedance
source of 1VP-P or the output of a 75

W terminated line.

The input is required to be AC coupled via a 0.1uF
coupling capacitor which allows for a nominal settling
time of 2ms. The luma output is capable of driving an AC
coupled 150

W load at 2VP-P or 1VP-P into a 75W load.

Up to 35pF of load capacitance (at the output pin) can be
driven without stability or slew issues. A 220µF AC
coupling capacitor is recommended at the output
(ML6428-1, -3 only).

CHROMINANCE (C) I/O

The chroma input is driven by a low impedance source of
0.7VP-P or the output of a 75

W terminated line. The input

is required to be AC coupled via a 0.1uF coupling
capacitor which allows for a nominal clamping time of
1ms. The chroma output is capable of driving an AC
coupled 150

W load at 2VP-P or 1VP-P into a 75W load.

Up to 35pF of load capacitance can be driven without
stability or slew issues. A 220µF AC coupling capacitor is
recommended at the output (ML6428-1, -3 only).

COMPOSITE VIDEO (CV) OUTPUT

The composite video output is capable of driving 2 CV
loads to 2VP-P and a high input impedance CV modulator.
It is intended to drive three devices: TV, VCR, and a
modulator. The TV or VCR input can be shorted to ground
and the other outputs will still meet specifications. Up to
35pF of load capacitance (at the output pin) can be
driven without stability or slew issues.

USING THE ML6428 FOR PAL APPLICATIONS

The ML6428 can be optimized for PAL video by adding
frequency peaking to the composite and S-video outputs.
Figures 7 and 8 illustrate the use of a additional external
capacitor, 330pF, added in parallel to the output source
termination resistor. This raises the frequency response
from 1.6 dB down at 4.8Mhz to 0.35dB down at 4.8MHz
allowing for accurate reproduction of the upper sideband
of the PAL subcarrier. Figure 9 shows the frequency
response of PAL video with various values of peaking
capacitors (0pF, 220pF, 270pF, 330pF) between 0 and
10MHz.

For NTSC applications without the peaking capacitor the
rejection at 27MHz is 42dB (typical) while for PAL
applications with the peaking capacitor the rejection at
27MHz is 38dB (typical). This is shown in Figure 10. The
differential group delay is shown in Figure 11 with and
without a peaking capacitor (0pF, 220pF, 270pF, and
330pF) varies slightly with capacitance, going from 8ns to
13ns.

FUNCTIONAL DESCRIPTION

ML6428

DATASHEET June, 2000

PERFORMANCE DATA

Figure 1. Passband Flatness

All outputs. (Normalized) Passband is ripple-free.

Figure 2. Passband/Stopband Rejection Ratios

All outputs. (Normalized)

Figure 4. DC Restore Performance of Luma Output

Luma ramp test pattern is shown to have minimal tilt

during vertical sync.

In most applications, the ML6428's input coupling

capacitors are 0.1µF. The Y input sinks 1.6µA during

active video, which tilts a horizontal line by 2mV at the

Y output

DELA

Y (ns)

FREQUENCY (MHz)

AMPLITUDE (dB)

FREQUENCY (MHz)

0.1

20

40

60

80

AMPLITUDE (dB)

FREQUENCY (MHz)

0.01

0.1

100

SCALE: 200ms/DIV

SCALE: 200mV/DIV

REGION OF TILT

Figure 3. Group Delay, all Outputs

Low frequency group delay is 62ns. At 3.58MHz group

delay increases by only 4ns. At 4.43MHz group delay

increases by only 7ns. The maximum deviation from flat

group delay of 12ns occurs at 6MHz.

ML6428

DATASHEET June, 2000

TYPICAL APPLICATIONS

Figure 5. AC Coupled S-Video and Composite Video Line Driver for NTSC

220µF

1µF

0.1µF

220µF

0.1µF

220µF

VIDEO CABLES

ML6428-1, -3

YOUT

CVOUT

ON-CHANNEL
MODULATOR,
VCR, AND TV

COUT

YIN

CIN

4th-ORDER

FILTER

4th-ORDER

FILTER

* C AND R DEPEND ON THE INPUT IMPEDANCE OF LOAD

Figure 6. DC Coupled S-Video and Composite Video Line Driver for NTSC

1µF

0.1µF

VIDEO CABLES

ML6428-2, -4

YOUT

CVOUT

ON-CHANNEL
MODULATOR,
VCR, AND TV

COUT

YIN

CIN

4th-ORDER

FILTER

4th-ORDER

FILTER

* C AND R DEPEND ON THE INPUT IMPEDANCE OF LOAD

ML6428

DATASHEET June, 2000

Figure 7. AC Coupled S-Video and Composite Video Line Driver for PAL

220µF

1µF

0.1µF

220µF

0.1µF

220µF

VIDEO CABLES

C1*

ML6428-1, -3

YOUT

CVOUT

ON-CHANNEL
MODULATOR,
VCR, AND TV

COUT

YIN

CIN

4th-ORDER

FILTER

4th-ORDER

FILTER

* C1, C2, AND R DEPEND ON THE INPUT IMPEDANCE OF LOAD

330pF

C2*

330pF

Figure 8. DC Coupled S-Video and Composite Video Line Driver for PAL

1µF

0.1µF

VIDEO CABLES

ML6428-2, -4

YOUT

CVOUT

ON-CHANNEL
MODULATOR,
VCR, AND TV

COUT

YIN

CIN

4th-ORDER

FILTER

4th-ORDER

FILTER

C1*

* C1, C2, AND R DEPEND ON THE INPUT IMPEDANCE OF LOAD

330pF

TYPICAL APPLICATIONS

ML6428

DATASHEET June, 2000

DS6428-02

PHYSICAL DIMENSIONS inches (millimeters)

ORDERING INFORMATION

PART NUMBER

TEMPERATURE RANGE

PACKAGE

ML6428CS-1

0°C to 70°C

8 Pin SOIC (S08)

ML6428CS-2

0°C to 70°C

8 Pin SOIC (S08)

ML6428CS-3

0°C to 70°C

8 Pin SOIC (S08)

ML6428CS-4

0°C to 70°C

8 Pin SOIC (S08)

Micro Linear Corporation

2092 Concourse Drive

San Jose, CA 95131

Tel: (408) 433-5200

Fax: (408) 432-0295

www.microlinear.com

SEATING PLANE

0.148 - 0.158

(3.76 - 4.01)

PIN 1 ID

0.228 - 0.244

(5.79 - 6.20)

0.189 - 0.199

(4.80 - 5.06)

0.012 - 0.020

(0.30 - 0.51)

0.050 BSC
(1.27 BSC)

0.015 - 0.035

(0.38 - 0.89)

0.059 - 0.069

(1.49 - 1.75)

0.004 - 0.010

(0.10 - 0.26)

0.055 - 0.061

(1.40 - 1.55)

0.006 - 0.010

(0.15 - 0.26)

0º - 8º

0.017 - 0.027

(0.43 - 0.69)

(4 PLACES)

Package: S08

8-Pin SOIC

Ð­Ð»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: ML6428CS-4

ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: ML6428CS-4