19-3267; Rev 2; 11/04
KIT
ATION
EVALU
BLE
AVAILA
Video-Signal Conditioners with AGC
and Back-Porch Clamp
General Description
Features
♦
Back-Porch Clamp to GND (MAX7450/MAX7451)
♦
Adjustable Back-Porch Clamp (MAX7452)
♦
Automatic Gain Control (±6dB Range) Normalizes
Signals to Standard Video Level
♦
Input Fault Detection with LOS Output
♦
Inherent 50Hz/60Hz Input Rejection of 60dB
♦
Single-Supply Operation: MAX7452 (+5V)
♦
Out-of-Band Noise Filter
♦
Output Buffer Drives Standard 150Ω Video Load
with 0dB or +6dB Gain
♦
Dual-Supply Operation
MAX7450 (±5V)
MAX7451 (±3.3V)
♦
Tiny 8-Pin SO Package
MAX7450/MAX7451/MAX7452
The MAX7450/MAX7451/MAX7452 complete front-end
video-signal conditioners are designed to improve the
quality of standard-definition video signals. The devices
restore the DC level of the video input, correct for
amplitude errors up to ±6dB, detect fault conditions,
and filter out-of-band noise. The MAX7450/MAX7451/
MAX7452 optimize the signal quality for further video
processing through a crosspoint switch or video
decoder (ADC). Each device integrates an input video
clamp, automatic gain control (AGC), loss-of-sync
(LOS) detector, and an out-of-band noise/lowpass filter.
These devices also incorporate a user-selectable
buffer gain (0 or +6dB) and an AGC-disable function.
The MAX7450 and MAX7451 operate from dual power
supplies of ±5V or ±3.3V respectively, and they restore
the video blanking level to GND. The MAX7452 operates
from a single +5V supply and features a user-adjustable
clamp level.
The devices are available in an 8-pin SO package with
an exposed pad and are specified for operation over
the extended (-40°C to +85°C) temperature range.
Ordering Information
PART
†
MAX7450ESA
MAX7451ESA
MAX7452ESA
TEMP RANGE
PIN-
SUPPLY
PACKAGE VOLTAGE (V)
±
5
±
3.3
Applications
Signal Conditioner for Standard-Definition
Video Inputs
Security Video Systems
Video-Switching Systems
-40°C to +85°C 8 SO-EP*
-40°C to +85°C 8 SO-EP*
-40°C to +85°C 8 SO-EP*
+5
*EP
= Exposed pad.
†
Package code = S8E-12.
Functional Diagram
V
CC
GAIN SET (0dB OR +6dB)
VIDEO
INPUT
IN
NOISE
FILTER
±6dB
0 OR +6dB
OUT
75Ω
75Ω
SYNC SEPARATOR
AND AMPLITUDE
DETECTOR
LOS
AGCD
MAX7450
MAX7451
V
SS
GND
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Video-Signal Conditioners with AGC
and Back-Porch Clamp
MAX7450/MAX7451/MAX7452
ABSOLUTE MAXIMUM RATINGS
V
CC
to GND
MAX7450/MAX7452...........................................................+6V
MAX7451 ...........................................................................+4V
V
SS
to GND
MAX7450.............................................................................-6V
MAX7451.............................................................................-4V
OUT
MAX7450/MAX7451 ..........................................-2.5V to +3.5V
MAX7452 ................................................-0.3V to (V
CC
+ 0.3V)
GSET, AGCD, LOS .....................................-0.3V to (V
CC
+ 0.3V)
All Other Pins
MAX7450/MAX7451...................(-0.3V + V
SS
) to (V
CC
+ 0.3V)
MAX7452 ................................................-0.3V to (V
CC
+ 0.3V)
Maximum Current into Any Pin ............……………………±50mA
Continuous Power Dissipation (T
A
= +70°C)
8-Pin SO (derate 18.9mW/°C above +70°C)..............1509mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Junction Temperature ......................................................+150°C
Lead temperature (soldering, 10s) ..................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
SUPPLY
= ±5V ±5% (MAX7450), V
SUPPLY
= ±3.3V ±5% (MAX7451), V
SUPPLY
= +5V ±5% (MAX7452), R
L
=150Ω to GND, C
L
= 0 to
20pF, GSET = 1, AGCD = 1, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Clamp Accuracy
Back-Porch Level Input Range
Clamp Response Time
V
BPLVL
t
CLAMP
SYMBOL
CONDITIONS
MAX7450/MAX7451, relative to GND
MAX7452, relative V
BPLVL
= 1.5V
MAX7452
GSET = 0
GSET = 1
1.5
1.2
70
±10
%
±10
-6.0
-0.3
10
f = 100kHz
Δt
G
dG
dθ
GSET = 0
GSET = 1
0.95
1.85
1
2
0.2
0.2
1.05
2.05
15
0.6
0.6
+6.0
+0.3
dB
dB
MHz
V/V
ns
%
Degrees
MIN
TYP
MAX
±50
±50
2.4
2.0
UNITS
mV
V
Lines
Blanking level at the output to 1% of final
value
GSET = 0, relative
to V
OUT
= 1V
P-P
GSET = 1, relative
to V
OUT
= 2V
P-P
AGC Accuracy
AGCD = 0,
V
IN
= 0.5V
P-P
to 2V
P-P
AGC Input Range
Gain Flatness
Noise-Filter Cutoff
Low-Frequency Gain
Group-Delay Deviation
Differential Gain
Differential Phase
G
F
Fc
AGCD = 0, relative to V
IN
= 1V
P-P
f = 5MHz relative to 100kHz
3.58/4.43MHz relative to 100kHz
Five-step modulated staircase (V
IN
= 1V
P-P
)
Five-step modulated staircase (V
IN
= 1V
P-P
)
2
_______________________________________________________________________________________
Video-Signal Conditioners with AGC
and Back-Porch Clamp
ELECTRICAL CHARACTERISTICS (continued)
(V
SUPPLY
= ±5V ±5% (MAX7450), V
SUPPLY
= ±3.3V ±5% (MAX7451), V
SUPPLY
= +5V ±5% (MAX7452), R
L
=150Ω to GND, C
L
= 0 to
20pF, GSET = 1, AGCD = 1, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
SYMBOL
CONDITIONS
Output signal
peak-to-peak to RMS
noise (100Hz to 5MHz)
18µs, 100 IRE bar
130 lines, 18µs, 100IRE bar
1
V
IN
= 1V
P-P
, dG / dP < 3% / degrees
AGCD = 1
Power-Supply Rejection Ratio
PSRR
V
CC
+ 100mV
P-P
,
f = 3.5MHz
MAX7450
Supply Current
MAX7451
MAX7452
Logic-High Input
Logic-Low Input
Logic-High Output
Logic-Low Output
Input Current Logic-High
Input Current Logic-Low
V
IH
V
IL
V
OH
V
OL
I
IH
I
IL
I
SOURCE
= 500µA
I
SINK
= 500µA
Logic input sink
Logic input source
V
CC
-
0.5
0.4
10
10
0.7 x
V
CC
0.3 x
V
CC
AGCD = 0 with
maximum gain
2
30
20
35
30
20
V
V
V
V
µA
µA
mA
dB
GSET = 0,
V
OUT
= 1V
P-P
GSET = 1,
V
OUT
= 2V
P-P
MIN
68
dB
65
0.2
0.5
5
2.4
%
%
µA
V
P-P
TYP
MAX
UNITS
MAX7450/MAX7451/MAX7452
Signal-to-Noise Ratio
SNR
Line Time Distortion
Field Time Distortion
Input Leakage Current
Output Dynamic Range
H
DIST
V
DIST
I
IN
_______________________________________________________________________________________
3
Video-Signal Conditioners with AGC
and Back-Porch Clamp
MAX7450/MAX7451/MAX7452
Typical Operating Characteristics
V
SUPPLY
= ±5V ±5% (MAX7450), V
SUPPLY
= ±3.3V ±5% (MAX7451), V
SUPPLY
= +5V ±5% (MAX7452), R
L
= 150Ω to GND, C
L
= 0 to
20pF, GSET = 1, AGCD = 1. T
A
= +25°C, unless otherwise noted.
GROUP DELAY vs. FREQUENCY
MAX7450 toc01
2T RESPONSE
DIFFERENTIAL PHASE (DEGREES) DIFFERENTIAL GAIN (%)
MAX7450 toc02
DIFFERENTIAL GAIN
0.2
0
-0.2
-0.4
1st
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
1st
2nd
3rd
4th
5th
6th
2nd
3rd
4th
5th
6th
MAX7450 toc03
60
0.4
50
GROUP DELAY (ns)
40
IN
200mV/div
30
DIFFERENTIAL PHASE
20
OUT
200mV/div
0.1
1
FREQUENCY (MHz)
10
t = 200ns/div
10
PASSBAND AMPLITUDE vs. FREQUENCY
MAX7450 toc04
AMPLITUDE vs. FREQUENCY
0
GAIN = 2V / V
-10
AMPLITUDE (dB)
-20
-30
-40
-50
-60
-70
GAIN = 1V / V
MAX7450 toc05
8
6
4
AMPLITUDE (dB)
2
0
-2
-4
-6
-8
-10
0.1
1
FREQUENCY (MHz)
GAIN = 1V / V
GAIN = 2V / V
10
10
0.1
1
10
100
FREQUENCY (MHz)
SUPPLY CURRENT vs. TEMPERATURE
MAX7450 toc06
BACK-PORCH VOLTAGE
vs. TEMPERATURE
MAX7450
BACK-PORCH VOLTAGE (mV)
-1
-2
-3
-4
-5
-6
MAX7450 toc07
35
MAX7450
33
SUPPLY CURRENT (mA)
0
31
29
27
25
-40
-15
10
35
60
85
TEMPERATURE (°C)
-40
-15
10
35
60
85
TEMPERATURE (°C)
4
_______________________________________________________________________________________
Video-Signal Conditioners with AGC
and Back-Porch Clamp
MAX7450/MAX7451/MAX7452
Typical Operating Characteristics (continued)
V
SUPPLY
= ±5V ±5% (MAX7450), V
SUPPLY
= ±3.3V ±5% (MAX7451), V
SUPPLY
= +5V ±5% (MAX7452), R
L
= 150Ω to GND, C
L
= 0 to
20pF, GSET = 1, AGCD = 1. T
A
= +25°C, unless otherwise noted.
OUTPUT BACK-PORCH LEVEL (MAX7450)
MAX7450 toc08
AGC RESPONSE ENVELOPE (V
IN
= 0.5V
P-P
)
MAX7450 toc09
AGC RESPONSE ENVELOPE (V
IN
= 2V
P-P
)
MAX7450 toc10
AGCD = 0
V
OUT
= 2V
P-P
IN
AC-COUPLED
200mV/div
500mV/div
OUT
200mV/div
BACK-PORCH = 0V
AGCD = 0
V
OUT
= 2V
P-P
500mV/div
1μs
400ms/div
400ms/div
Pin Description
PIN
MAX7450/
MAX7451
1
2
3
4
—
5
6
7
8
—
MAX7452
1
2
3
—
4
5
6
7
8
—
NAME
FUNCTION
Positive Power Supply. Connect +5V to V
CC
for the MAX7450/MAX7452. Connect +3.3V to V
CC
for the MAX7451. Bypass to GND with 1µF and 0.1µF capacitors as close to the pin as possible.
Video Input. AC-couple video signal through a 0.1µF capacitor.
Ground
Negative Power Supply. Connect -5V to V
SS
for the MAX7450. Connect -3.3V to V
SS
for the
MAX7451. Bypass to GND with 1µF and 0.1µF capacitors as close to the pin as possible.
Back-Porch Level Input. When gain = 2V/V (GSET = 1), output back-porch level is equal to
BPLVL input. When gain = 1V/V (GSET = 0), output back-porch level is equal to V
BPLVL
/1.5.
Automatic Gain-Control Disable Input. Disable AGC by driving AGCD to V
CC
. Enable AGC by
driving AGCD to GND.
Video Output
Gain-Setting Input. Drive GSET high to set buffer gain to +6dB. Drive GSET low to set buffer
gain to 0dB.
Loss-of-Sync Logic Output. LOS is high when video sync is lost for more than 15 horizontal
lines. LOS goes low when video sync is present.
Exposed Pad. Connect to V
SS
(MAX7450/MAX7451). Connect to GND (MAX7452).
V
CC
IN
GND
V
SS
BPLVL
AGCD
OUT
GSET
LOS
EP
_______________________________________________________________________________________
5
实时操作系统RTOS
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
