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參數(shù)資料
| 型號(hào)： | MAX7474EAE+ |
| 廠商： | Maxim Integrated Products |
| 文件頁(yè)數(shù)： | 8/10頁(yè) |
| 文件大?。?/td> | 0K |
| 描述： | IC ADAPTV EQ VID OVER UTP 16SSOP |
| 產(chǎn)品培訓(xùn)模塊： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 標(biāo)準(zhǔn)包裝： | 76 |
| 類型： | 均衡器 |
| 應(yīng)用： | 安全系統(tǒng) |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 16-SSOP（0.209"，5.30mm 寬） |
| 供應(yīng)商設(shè)備封裝： | 16-SSOP |
| 包裝： | 管件 |
MAX7474
Adaptive Equalizer for
Video Over Twisted Pair
_______________________________________________________________________________________
7
The chroma gain for the MAX7474 is automatically
adjusted between 0dB and +12dB, while the low-fre-
quency 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.
Automatic Gain Control (AGC)
The automatic gain control circuit corrects low-frequen-
cy signal losses such that the output signal obtains a
nominal sync level (VSYNC_OUT) of 293mV. Differential
input sync pulse amplitude in the 210mVP-P and
600mVP-P range is automatically adjusted to the nomi-
nal 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-imped-
ance 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 auto-
matically 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.
Fixed Equalization Mode (LOB Is High)
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).
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 equaliza-
tion 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 (VLOB) of 80mVP-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 dri-
ver with 0dB gain. The typical output voltage swing of
the output driver is 1.2VP-P. The output driver is capa-
ble of driving two AC-coupled or DC-coupled 150
video loads. The output back-porch DC level is set by
an internal back-porch clamp circuit (see the
Back-
Porch 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 approxi-
mately equal to the voltage level on the BPLVL input. The
voltage range allowed at the BPLVL input is 1V to 1.6V.
Applications Information
Differential UTP Input Interface
Applications with differential input interface require
proper input voltage levels, termination, and AC-cou-
pling (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 50 to ground at
INN and INP inputs. Apply a 0.022F coupling capaci-
tor at each input.
Output Interface
The video output is capable of driving an AC-coupled
or DC-coupled load. Use a 220F 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
Table 1. Fixed Equalization Level Settings
PART
FEQ1
FEQ0
TYP (dB)
CABLE LENGTH
RANGE (m)
GND
0
0 to 75
GND
VCC
4.5
75 to 225
MAX7474
VCC
X
10.5
≥ 225
X = VCC or GND.
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參數(shù)描述 |
|---|---|
| MAX7474EAE+ | 功能描述:視頻 IC Adaptive Equalizer f/Vid Over Twist Pr RoHS:否 制造商:Fairchild Semiconductor 工作電源電壓:5 V 電源電流:80 mA 最大工作溫度:+ 85 C 封裝 / 箱體:TSSOP-28 封裝:Reel |
| MAX7474EAE+T | 功能描述:視頻 IC Adaptive Equalizer f/Vid Over Twist Pr RoHS:否 制造商:Fairchild Semiconductor 工作電源電壓:5 V 電源電流:80 mA 最大工作溫度:+ 85 C 封裝 / 箱體:TSSOP-28 封裝:Reel |
| MAX7474EVKIT+ | 功能描述:視頻 IC 開發(fā)工具 MAX7474 Eval Kit RoHS:否 制造商:Texas Instruments 產(chǎn)品:Evaluation Boards 類型:YPbPr to RGBHV Converters 工具用于評(píng)估:LMH1251 工作電源電壓:5 V |
| MAX747CPD | 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| MAX747CPD+ | 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
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