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參數(shù)資料
| 型號： | MAX9584 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Dual, Triple, and Quad Standard-Definition Video Filter Amplifiers with DC-Coupled Input Buffers |
| 中文描述： | 雙、三和四通道標(biāo)清視頻濾波放大器，提供直流耦合輸入緩沖器 |
| 文件頁數(shù)： | 8/15頁 |
| 文件大?。?/td> | 351K |
| 代理商： | MAX9584 |
M
Dual, Triple, and Quad Standard-Definition Video
Filter Amplifiers with DC-Coupled Input Buffers
8
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Detailed Description
The MAX9583/MAX9584/MAX9585 filter and amplify the
video DAC output in applications such as set-top boxes
and televisions. These devices consist of input buffers,
lowpass filters, and gain of 2V/V output amplifiers capa-
ble of driving a standard 150
video load to ground.
Inputs
The video inputs should be directly connected to the
output of the video current DAC. DC coupling ensures
that the input signals are ground referenced so that the
sync tip of composite or luma signals is within 50mV of
ground and the blank level of the chroma signal is
between 0.5V and 0.65V. Since the input buffers are
identical, any standard-definition video signal can be
applied to those inputs provided the signal is between
ground and 1.05V when V
DD
= 2.7V. For example,
three composite video signals could be applied to INA,
INB, and INC of the MAX9584. The RGB set or the
YPbPr set can also be inputs to INA, INB, and INC of
the MAX9584.
Video Filter
The filter passband (±1dB) is typically 7MHz, which
makes the device suitable for standard-definition video
signals from all sources (e.g., broadcast and DVD).
Broadcast video signals are channel limited: NTSC sig-
nals have 4.2MHz bandwidth and PAL signals have
5MHz bandwidth. Video signals from a DVD player,
however, are not channel limited, so the bandwidth of
DVD video signals can approach the Nyquist limit of
6.75MHz. (Recommendation ITU-R BT.601-5 specifies
13.5MHz as the sampling rate for standard-definition
video). Therefore, the maximum bandwidth of the signal
is 6.75MHz. To ease the filtering requirements, most
modern video systems oversample by two times, clock-
ing the video current DAC at 27MHz.
Outputs
The video output amplifiers can both source and sink
load current, allowing output loads to be DC- or AC-
coupled. The amplifier output stage needs approxi-
mately 300mV of headroom from either supply rail. The
devices have an internal level-shift circuit that positions
the sync tip at approximately 300mV at the output. The
blank level of the chroma output is positioned at
approximately 1.3V if the blank level of the chroma
input signal is 0.5V. The blank level of the chroma out-
put is positioned at approximately 1.5V if the blank level
of the chroma input signal is 0.6V.
If the supply voltage is greater than 3.135V (5% below
a 3.3V supply), each amplifier can drive two DC-cou-
pled video loads to ground. If the supply is less than
3.135V, each amplifier can drive only one DC-coupled
or AC-coupled video load.
Applications Information
Reducing Power Consumption
in the Video DACs
The MAX9583/MAX9584/MAX9585 have high-imped-
ance input buffers that work with source resistances as
high as 300
. To reduce power dissipation in the video
DACs, the DAC output resistor can be scaled up in
value. The reference resistor that sets the reference cur-
rent inside the video DACs must also be similarly scaled
up. For instance, if the output resistor is 37.5
, the DAC
must source 26.7mA when the output is 1V. If the output
resistor is increased to 300
, then the DAC only needs
to source 3.33mA when the output is 1V.
There is parasitic capacitance from the DAC output to
ground. That capacitance, in parallel with the DAC out-
put resistor, forms a pole that can potentially roll off the
frequency response of the video signal. For example,
300
in parallel with 50pF create a pole at 10.6MHz. To
minimize this capacitance, reduce the area of the sig-
nal trace attached to the DAC output as much as possi-
ble, and place the MAX9583/MAX9584/MAX9585 as
close as possible to the video DAC outputs.
AC-Coupling the Outputs
The outputs can be AC-coupled since the output stage
can source and sink current as shown in Figure 1.
Coupling capacitors should be 220μF or greater to
keep the highpass filter, formed by the 150
equivalent
resistance of the video transmission line, to a corner
frequency of 4.8Hz or below. The frame rate of PAL
systems is 25Hz, and the frame rate of NTSC systems
is 30Hz. The corner frequency should be well below the
frame rate.
Power-Supply Bypassing and Ground
The MAX9583/MAX9584/MAX9585 operate from a single-
supply voltage down to 2.7V, allowing for low-power opera-
tion. Bypass V
DD
to GND with a 0.1μF capacitor. Place all
external components as close as possible to the device.
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| MAX9585 | Dual, Triple, and Quad Standard-Definition Video Filter Amplifiers with DC-Coupled Input Buffers |
| MAX9586_0710 | Single, Dual, Triple, and Quad Standard-Definition Video Filter Amplifiers with AC-Coupled Input Buffers |
| MAX9586 | Single, Dual, Triple, and Quad Standard-Definition Video Filter Amplifiers with AC-Coupled Input Buffers |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX9584AUA+ | 功能描述:視頻放大器 Standard-Definition Video Filter Amp RoHS:否 制造商:ON Semiconductor 通道數(shù)量:4 電源類型: 工作電源電壓:3.3 V, 5 V 電源電流: 最小工作溫度: 最大工作溫度: 封裝 / 箱體:TSSOP-14 封裝:Reel |
| MAX9584AUA+T | 功能描述:視頻放大器 Standard-Definition Video Filter Amp RoHS:否 制造商:ON Semiconductor 通道數(shù)量:4 電源類型: 工作電源電壓:3.3 V, 5 V 電源電流: 最小工作溫度: 最大工作溫度: 封裝 / 箱體:TSSOP-14 封裝:Reel |
| MAX9584EVKIT+ | 制造商:Maxim Integrated Products 功能描述:MAX9584 EVAL KIT - Rail/Tube |
| MAX9585AUB+ | 功能描述:視頻放大器 Standard-Definition Video Filter Amp RoHS:否 制造商:ON Semiconductor 通道數(shù)量:4 電源類型: 工作電源電壓:3.3 V, 5 V 電源電流: 最小工作溫度: 最大工作溫度: 封裝 / 箱體:TSSOP-14 封裝:Reel |
| MAX9585AUB+T | 功能描述:視頻放大器 Standard-Definition Video Filter Amp RoHS:否 制造商:ON Semiconductor 通道數(shù)量:4 電源類型: 工作電源電壓:3.3 V, 5 V 電源電流: 最小工作溫度: 最大工作溫度: 封裝 / 箱體:TSSOP-14 封裝:Reel |
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