MAXIM MAX7474EAE

19-3216; Rev 0; 1/08
KIT
ATION
EVALU
E
L
B
AVAILA
Adaptive Equalizer for
Video Over Twisted Pair
Features
The MAX7474 adaptive equalizer recovers losses
incurred in the transmission of a composite video
(CVBS) signal over unshielded twisted-pair (UTP)
cable. The device fully recovers losses for cable
lengths of up to 300m and greatly improves signal quality for cable lengths of up to 600m. The device automatically adapts to all cable lengths for CVBS signals with
color burst and allows fixed-equalization settings for
video signals without burst. The MAX7474 is optimized
to provide compensation for losses that occur when
transmitting composite video signals over UTP cables
such as Category 5e. The device compensates for low
frequency and chroma band losses. The MAX7474 is
compatible with NTSC and PAL standards.
The MAX7474 accepts differential input and provides a
single-ended output. The output is capable of driving
two AC- or DC-coupled standard 150Ω video loads.
The output back-porch DC level is adjustable with an
externally applied DC voltage at the BPLVL input. The
device also features loss-of-sync (LOS) and loss-of-burst
(LOB) logic outputs.
The MAX7474 is available in a 16-pin SSOP package
and is fully specified over the extended (-40°C to
+85°C) temperature range.
♦ Automatically Equalizes Up to 600m
(Fully Recovers Losses Up to 300m) of UTP Cable
Carrying CVBS
♦ Automatic Switchover to Fixed Equalization for
CVBS Without Color Burst
♦ Integrated Video Driver with Adjustable
Back-Porch Clamp Level
♦ LOS and LOB Output
♦ NTSC and PAL Compatible
♦ 16-Pin SSOP Package
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX7474EAE+
-40°C to +85°C
16 SSOP
(5.3mm x 6.2mm)
PKG
CODE
A16+2
+Denotes a lead-free package.
Applications
Security Video Systems
Pin Configuration and Typical Application Circuit appear at
end of data sheet.
Video Switching Systems
Home Automation
Functional Diagram
+5V
+5V
0.1µF
0.1µF
VCC
VCC
0.022µF
INP
UNSHIELDED TWISTED PAIR
(0 TO 300m)
MAX7474
CLAMP
CAMERA
ADAPTIVE
EQUALIZER
OUT
ADC
INN
50Ω
BACK-PORCH
CLAMP
0.022µF
50Ω
FEQ0
FEQ1
AGC AND AEQ
CONTROL
BPLVL (1.0V TO 1.6V)
LOB
LOS
GND
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1
MAX7474
General Description
MAX7474
Adaptive Equalizer for
Video Over Twisted Pair
ABSOLUTE MAXIMUM RATINGS
VCC to GND ..............................................................-0.3V to +6V
All Other Pins to GND.............-0.3V to (min of 6V or VCC + 0.3V)
Maximum Continuous Current into Any Input or Output .....±50mA
Continuous Power Dissipation (TA = +70°C)
16-Pin SSOP (derate 7.1mW/°C above +70°C) ........571.4mW
Operating Temperature Range ...........................-40°C to +85°C
Maximum Junction Temperature .....................................+150°C
Storage Temperature Range .............................-65°C to +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
(VCC = +4.75V to +5.25V, RL = 150Ω (AC-coupled), FEQ1 = GND, FEQ0 = GND, VBPLVL = 1.4V, TA = -40°C to +85°C, unless otherwise
noted. Typical values are at TA = +25°C.)
PARAMETER
Differential Input
Operating Voltage
SYMBOL
VIN-DIFF
Maximum Differential
Input Operating Voltage
Output Voltage
CONDITIONS
AC-coupled, measured from sync tip to 100% white level
(Note 1)
AC-coupled, measured from sync tip to 100% white level
VOUT
MIN
TYP
MAX
1.0
VP-P
2.4
Measured from sync tip to 100% white level
UNITS
VP-P
1.0
VP-P
Output Sync Accuracy
VSYNC_OUT
210mVP-P < VSYNC_IN-DIFF < 600mVP-P
263
293
323
mVP-P
Output Burst Accuracy
VBURST_OUT
76mVP-P < VBURST_IN-DIFF < 300mVP-P, fSC = 3.58MHz
242
293
344
mVP-P
Differential Phase
DP
0.3
Degrees
Differential Gain
DG
0.3
%
Clamp Settling Time
tCLAMP
Back-Porch Level Input
Operating Range
VBPLVL
Output Blank Level
Accuracy
∆VOUT-BL
Output blank level settles to < 5 IRE of final value from an
initial 100 IRE input error
9
1.0
(Note 2)
30
H Lines
1.6
V
±55
mV
Line-Time Distortion
LTD
18µs, 100 IRE bar, DC-coupled output
1.2
%
LOS Threshold
VLOS
Measured differentially between INP and INN (Note 3)
40
mVP-P
LOB Threshold
VLOB
Measured at OUT with maximum equalizer gain (Note 4)
80
mVP-P
16,384
H Lines
Equalizer Response
Time
tEQ
Within ±10% of final value of the combined AGC and
AEQ gain from minimum to maximum
OUT Leakage Current
ILEAK
LOS mode, OUT is three-stated
Fixed Equalizer Gain
AFEQ
fSC = 3.58MHz
2
±0.01
±10
+1.5
FEQ1 = GND, FEQ0 = GND
-1.5
0
FEQ1 = GND, FEQ0 = VCC
2.5
4.5
6.5
FEQ1 = VCC, FEQ0 = GND
8.5
10.5
12.5
_______________________________________________________________________________________
µA
dB
Adaptive Equalizer for
Video Over Twisted Pair
(VCC = +4.75V to +5.25V, RL = 150Ω (AC-coupled), FEQ1 = GND, FEQ0 = GND, VBPLVL = 1.4V, TA = -40°C to +85°C, unless otherwise
noted. Typical values are at TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DIGITAL INPUTS (FEQ0, FEQ1)
Input High Voltage
VIH
Input Low Voltage
VIL
Input Leakage Current
Input Capacitance
0.7 x
VCC
Digital inputs = 0 or VCC
V
±0.01
CIN
0.3 x
VCC
V
±10
µA
15
pF
DIGITAL OUTPUTS (LOS, LOB)
Output Low Voltage
VOL
ISINK = 500µA
Output High Voltage
VOH
ISOURCE = 500µA
0.4
VCC
- 0.4
V
V
POWER SUPPLY
Supply Voltage Range
Supply Current
DC Power-Supply
Rejection Ratio
VCC
ICC
PSRR
4.75
No load
5.0
5.25
Normal mode
47
59
LOS mode
24
20log(∆VCC/∆VOUT-BlackLevel), black video input with no
color burst
65
V
mA
dB
Note 1: VIN-DIFF = VINP - VINN.
Note 2: VOUT-BL = VBPLVL + ∆VOUT-BL.
Note 3: LOS is high when the input video sync amplitude goes below VLOS for 32 consecutive horizontal lines. LOS goes low when
the input video sync amplitude exceeds VLOS for 32 consecutive horizontal lines.
Note 4: LOB is high when the output color burst amplitude goes below VLOB for 32 consecutive horizontal lines when at maximum
equalizer gain. LOB goes low when the output color burst amplitude exceeds VLOB for 32 consecutive horizontal lines.
_______________________________________________________________________________________
3
MAX7474
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(VCC = 5V, RL = high impedance, fSC = 3.58MHz, Category 5e cable with active driver, TA = +25°C.)
MULTIBURST (0.5m CABLE)
75% COLOR BAR VECTOR DIAGRAM
(0.5m CABLE)
MULTIBURST (300m CABLE)
MAX7474 toc01
MAX7474 toc02
MAX7474 toc03
VINP-VINN
200mV/div
VINP-VINN
200mV/div
VOUT
200mV/div
VOUT
200mV/div
10µs/div
75% COLOR BAR VECTOR DIAGRAM
(300m CABLE)
DIFFERENTIAL GAIN AND PHASE
(300m CABLE)
0.4
MAX7474 toc05
MAX7474 toc04
0.2
0
-0.2
-0.4
0.4
0.2
0
-0.2
-0.4
0
1
2
3
4
DIFFERENTIAL PHASE (°) DIFFERENTIAL GAIN (%)
DIFFERENTIAL GAIN AND PHASE
(0.5m CABLE)
0.4
0.2
0
-0.2
-0.4
1
2
3
5
MAX7474 toc09
VINP-VINN
200mV/div
VOUT
200mV/div
200ns/div
4
12.5T RESPONSE (0.5m CABLE)
VINP-VINN
200mV/div
VOUT
200mV/div
4
-0.4
MAX7474 toc08
VINP-VINN
200mV/div
200ns/div
0
-0.2
MODULATED STEP
2T RESPONSE (300m CABLE)
MAX7474 toc07
0.2
0
5
MODULATED STEP
2T RESPONSE (0.5m CABLE)
0.4
MAX7474 toc06
10µs/div
DIFFERENTIAL PHASE (°) DIFFERENTIAL GAIN (%)
MAX7474
Adaptive Equalizer for
Video Over Twisted Pair
VOUT
200mV/div
500ns/div
_______________________________________________________________________________________
Adaptive Equalizer for
Video Over Twisted Pair
18µs LINE-TIME DISTORTION
(300m CABLE)
18µs LINE-TIME DISTORTION
(0.5m CABLE)
12.5T RESPONSE (300m CABLE)
MAX7474 toc10
MAX7474 toc12
MAX7474 toc11
VINP-VINN
200mV/div
VINP-VINN
200mV/div
VINP-VINN
200mV/div
VOUT
200mV/div
VOUT
200mV/div
VOUT
200mV/div
500ns/div
5µs/div
5µs/div
NOISE SPECTRUM
(300m CABLE)
MAX7474 toc13
0
-5
-10
-15
-20
-25
-30
-40
-45
-50
-55
-60
-65
-70
-75
-80
-85
-90
-95
-100
NOISE LEVEL (dB)
NOISE LEVEL (dB)
NOISE SPECTRUM
(0.5m CABLE)
1
2
3
4
FREQUENCY (MHz)
5
MAX7474 toc14
0
-5
-10
-15
-20
-25
-30
-40
-45
-50
-55
-60
-65
-70
-75
-80
-85
-90
-95
-100
1
2
3
4
5
FREQUENCY (MHz)
_______________________________________________________________________________________
5
MAX7474
Typical Operating Characteristics (continued)
(VCC = 5V, RL = high impedance, fSC = 3.58MHz, Category 5e cable with active driver, TA = +25°C.)
Adaptive Equalizer for
Video Over Twisted Pair
MAX7474
Pin Description
PIN
NAME
1, 2, 3,
5, 10, 13
GND
Ground. Connect all GND terminals together.
4, 9
VCC
Power-Supply Input. Connect a +4.75V to +5.25V supply to VCC. Connect both VCC inputs together.
Bypass each VCC input with a 0.1µF capacitor to GND as close as possible to the device.
6
LOB
Loss-of-Burst Logic Output. LOB goes high when the output color burst goes below the LOB threshold
(VLOB) for 32 consecutive horizontal lines when the equalizer is at its maximum gain. LOB goes low
when the output color burst exceeds VLOB for 32 consecutive horizontal lines. When LOB is active, the
device enters the fixed equalization mode. LOB is valid only when LOS is low.
7
BPLVL
8
OUT
11
FEQ0
12
FEQ1
FUNCTION
Back-Porch Level Input. The voltage applied to BPLVL sets the output back-porch voltage level.
Composite Video Output
Fixed-Cable Equalization inputs. FEQ0 and FEQ1 set the fixed equalization level. See Table 1.
14
INP
Noninverted Video Input. AC-couple video signal with a 0.022µF capacitor.
15
INN
Inverted Video Input. AC-couple video signal with a 0.022µF capacitor.
LOS
Loss-of-Sync Logic Output. LOS goes high when the input sync amplitude goes below the loss-of-sync
threshold (VLOS) for 32 consecutive horizontal lines. LOS is pulled low when the input sync amplitude
exceeds VLOS for 32 consecutive horizontal lines. When LOS is active, the output enters a highimpedance state.
16
Detailed Description
The MAX7474 compensates for cable losses that
occur when transmitting a composite video signal over
unshielded twisted-pair cable (see the Typical
Application Circuit). The device automatically adapts
to cable length by monitoring the sync and color-burst
amplitudes of the color video signal at the output
(OUT) and adjusting the gains accordingly. Video signals without burst are automatically detected and a
user-selectable fixed equalization is applied to the signal. The MAX7474 provides full equalization up to
300m of Category 5e cable and greatly improves performance up to 600m.
The MAX7474 accepts differential video input signals in
NTSC or PAL standards. The MAX7474 includes an
output unity-gain video driver and adjustable backporch DC level. The device also features LOS and LOB
logic outputs.
Video Input
The MAX7474 accepts a differential video input with a
maximum 2.4VP-P voltage swing. A twisted-pair cable
carries the differential video signal to the positive (INP)
and negative (INN) inputs, which are AC-coupled with
0.022µF capacitors. Each input is internally clamped to
a DC level (see the Input Clamp section).
6
Input Clamp
The MAX7474 clamps the sync tip of the input signal to
internally set DC levels effectively correcting, on a lineby-line basis, any shift in the sync-tip level of the input
video signal. The sync-tip of the positive video input
signal (VINP) is clamped to typically 2.0V and the negative video input signal (VINN) is clamped to typically
3.2V. The input clamp enables capacitive coupling of
the input, permitting a large common-mode DC difference between the line driver (camera) and the device.
Adaptive Equalizer
The adaptive equalizer in the MAX7474 provides the
appropriate inverse frequency response needed to
compensate for UTP cable loss. The equalizer adjusts
the low-frequency amplitude and chroma amplitude of
the input CVBS signal. The low-frequency component
of the CVBS is adjusted according to the feedback
information obtained from the internal automatic gaincontrol (AGC) circuit, which monitors the sync pulse
amplitude of the output signal (see the Automatic Gain
Control (AGC) section). The chroma gain of the video
signal is adjusted according to the feedback information obtained from the internal automatic equalization
control circuit, which monitors the color-burst amplitude
of the output signal (see the Automatic Equalization
Control (AEQ) section).
_______________________________________________________________________________________
Adaptive Equalizer for
Video Over Twisted Pair
Automatic Gain Control (AGC)
The automatic gain control circuit corrects low-frequency signal losses such that the output signal obtains a
nominal sync level (VSYNC_OUT) of 293mV. Differential
input sync pulse amplitude in the 210mV P-P and
600mVP-P range is automatically adjusted to the nominal output sync level (VSYNC_OUT).
If the sync is lost for 32 consecutive horizontal lines, the
LOS output goes high and OUT is set to a high-impedance state.
Automatic Equalization Control (AEQ)
The automatic equalization control circuit corrects the
chroma signal attenuation such that the output-signal
burst amplitude is 293mV (subcarrier frequency, fSC =
3.58MHz or 4.43MHz). Differential input color-burst
amplitude in the 76mVP-P and 300mVP-P range is automatically adjusted to the nominal output color-burst
level (VBURST_OUT).
The AGC and AEQ equalization take approximately 1s
(16,384 lines) to change from the lowest gain to the
highest gain. During this time, the chroma amplitude is
gradually increased from minimum to maximum.
When using cable lengths greater than 75m, set the
fixed equalization level according to Table 1, or higher,
to ensure the device comes out of the fixed equalization mode. If the fixed equalization is set to a lower gain
setting than specified in Table 1, the amplitude of the
color-burst signal at the output may remain smaller than
the LOB threshold (V LOB ) of 80mV P-P , keeping the
device in LOB mode (see the Automatic Equalization
Control (AEQ) section). If the conditions in Table 1 are
not met, set FEQ1 to high to ensure the device always
comes out of LOB mode for longer cable lengths.
Output Video Driver
The MAX7474 features a single-ended video output driver with 0dB gain. The typical output voltage swing of
the output driver is 1.2VP-P. The output driver is capable of driving two AC-coupled or DC-coupled 150Ω
video loads. The output back-porch DC level is set by
an internal back-porch clamp circuit (see the BackPorch Clamp section). OUT enters a high-impedance
state when sync is lost for 32 consecutive horizontal
lines, asserting LOS.
Back-Porch Clamp
The MAX7474 features a back-porch clamp to set the
output blanking level. This clamp shifts the DC level of
the video signal so that the back-porch level is approximately equal to the voltage level on the BPLVL input. The
voltage range allowed at the BPLVL input is 1V to 1.6V.
Applications Information
Fixed Equalization Mode (LOB Is High)
Differential UTP Input Interface
If the color-burst amplitude at the output of the
MAX7474 (OUT) is less than 80mVP-P with the equalizer
gain set to maximum for 32 consecutive horizontal
lines, the loss-of-burst output (LOB) goes high. LOB
returns low when color bursts with amplitude greater
than 80mVP-P are present at OUT for 32 consecutive
horizontal lines.
For applications where the input signal has no color
burst, or the input burst amplitude is lower than the LOB
threshold voltage (VLOB), the MAX7474 asserts LOB and
automatically applies a user-defined fixed equalization
set by logic inputs FEQ1 and FEQ0 (see Table 1).
Applications with differential input interface require
proper input voltage levels, termination, and AC-coupling (Figure 1). The maximum differential input voltage
swing allowed is 2.4V. Use active drivers to drive the
cable as shown in Figure 1. For Category 5e cables,
the proper termination resistance is 50Ω to ground at
INN and INP inputs. Apply a 0.022µF coupling capacitor at each input.
Table 1. Fixed Equalization Level Settings
PART
MAX7474
TYP (dB)
CABLE LENGTH
RANGE (m)
FEQ1
FEQ0
GND
GND
0
0 to 75
GND
VCC
4.5
75 to 225
VCC
X
10.5
≥ 225
Output Interface
The video output is capable of driving an AC-coupled
or DC-coupled load. Use a 220µF or larger coupling
capacitor for AC-coupling. Figure 1 shows applications
with AC- and DC-coupled output interface.
Security Systems Application
Security systems typically consist of many cameras that
are viewed and recorded on a relatively smaller number
X = VCC or GND.
_______________________________________________________________________________________
7
MAX7474
The chroma gain for the MAX7474 is automatically
adjusted between 0dB and +12dB, while the low-frequency gain is automatically adjusted between -6dB
and +3.6dB, providing full equalization for cable losses
that can occur when using up to 300m of UTP cable to
transmit CVBS signal with color burst.
MAX7474
Adaptive Equalizer for
Video Over Twisted Pair
CAMERA
+0.5VP-P
1VP-P
50Ω
0.022µF
MAX7474
CAT 5e
(0 TO 600m)
1VP-P
ADC
CVBS
0.022µF
50Ω
-0.5VP-P
50Ω
CAMERA
+0.5VP-P
1VP-P
50Ω
BPLVL
50Ω
0.022µF
MAX7474
CAT 5e
(0 TO 600m)
1VP-P
220µF 75Ω
CVBS
0.022µF
50Ω
-0.5VP-P
50Ω
50Ω
Figure 1. Typical Input and Output Connections
of monitors or recording devices. Cabling is a significant part of a CCTV installation cost. Low-cost
unshielded twisted-pair (UTP) cable has increasingly
replaced coaxial cable in security systems. Most cameras and switchers use single-channel coax connectors, and therefore require some type of
single-ended-to-differential video conversion such as
active drivers. Active cable compensation is required
for longer cable lengths. Active compensation can
occur on the receive side, camera side, or both. The
MAX7474 provides active compensation on the receive
side that is superior to balun, or active fixed cable
equalization.
8
Power Supply, Grounding, and Layout
The MAX7474 operates from a +4.75V to +5.25V single
supply. Connect both VCC inputs together and bypass
each one with a 0.1µF capacitor to GND. Connect the
0.1µF capacitors as close as possible to the device to
minimize the loop formed when the bypass capacitor is
connected to the device, thus avoiding additional
inductance that could resonate with the capacitor. For
optimum performance, use a ground plane and keep
the input and output traces away from each other.
Chip Information
PROCESS: BiCMOS
_______________________________________________________________________________________
Adaptive Equalizer for
Video Over Twisted Pair
MAX7474
Pin Configuration
TOP VIEW
GND
1
16 LOS
GND
2
15 INN
GND
3
14 INP
13 GND
VCC
4
GND
5
12 FEQ1
LOB
6
11 FEQ0
BPLVL
7
10 GND
OUT
8
9
MAX7474
VCC
SSOP
Typical Application Circuit
VCC
VCC
JU2
1
2
JU1
1
2
3
3
J1
11
12
13
VCC
VCC
4
9
C6
0.1µF
C3
0.1µF
5
GND
10
14
VIN-8
VIN-7
VIN-6
R1
49.9Ω
1%
VIN-3
VIN-2
VIN-1
GND
U1
LOS
MAX7474
GND
GND
VCC
GND
15
J1-1
16
J1-2
J1-3
1
2
3
VCC
JU4
GND
GND
OUT
VOUT
8
R3
0Ω
C7
470µF
INP
BP_LVL
C5
V_INN
0.022µF
BPLVL
INN
JU3
7
3
2
1
R2
49.9Ω
1%
VIN-5
VIN-4
FREQ1
LOB
C4
0.022µF
V_INP
VIN
FREQ0
6
VCC
GND
3
4
C1
1µF
2
SHDN
IN
GND
U2
OUT
5
1
C2
1µF
MAX6037
N.C.
2
3
R4
10kΩ
1
_______________________________________________________________________________________
9
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
2
SSOP.EPS
MAX7474
Adaptive Equalizer for
Video Over Twisted Pair
1
INCHES
E
H
MILLIMETERS
DIM
MIN
MAX
MIN
MAX
A
0.068
0.078
1.73
1.99
A1
0.002
0.008
0.05
0.21
B
0.010
0.015
0.25
0.38
C
0.20
0.09
0.004 0.008
SEE VARIATIONS
D
E
e
0.205
0.212
0.0256 BSC
5.20
MILLIMETERS
INCHES
D
D
D
D
D
5.38
MIN
MAX
MIN
MAX
0.239
0.239
0.278
0.249
0.249
0.289
6.07
6.07
7.07
6.33
6.33
7.33
0.317
0.397
0.328
0.407
8.07
10.07
8.33
10.33
N
14L
16L
20L
24L
28L
0.65 BSC
H
0.301
0.311
7.65
7.90
L
0.025
0∞
0.037
8∞
0.63
0∞
0.95
8∞
N
A
C
B
e
A1
L
D
NOTES:
1. D&E DO NOT INCLUDE MOLD FLASH.
2. MOLD FLASH OR PROTRUSIONS NOT TO EXCEED .15 MM (.006").
3. CONTROLLING DIMENSION: MILLIMETERS.
4. MEETS JEDEC MO150.
5. LEADS TO BE COPLANAR WITHIN 0.10 MM.
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, SSOP, 5.3 MM
APPROVAL
DOCUMENT CONTROL NO.
21-0056
REV.
C
1
1
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2008 Maxim Integrated Products
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is a registered trademark of Maxim Integrated Products, Inc.