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參數資料
| 型號： | AD8041 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | 160 MHz Rail-to-Rail Amplifier with Disable |
| 中文描述： | 160 MHz的軌到軌放大器具有禁用 |
| 文件頁數： | 13/16頁 |
| 文件大小： | 438K |
| 代理商： | AD8041 |
AD8041
REV. 0
–13–
APPLICATIONS
RGB Buffer
The AD8041 can provide buffering of RGB signals that include
ground while operating from a single +3 V or +5 V supply.
The signals that drive an RGB monitor are usually supplied by
current output DACs that operate from a +5 V only supply.
These can triple DACs like the ADV7120 and ADV7122 from
Analog Devices or integrated into the graphics controller IC as
in most PCs these days.
During the horizontal blanking interval the currents output from
the DACs go to zero and the RGB signals are pulled to ground
via the termination resistors. If more than one RGB monitor is
desired, it cannot simply be connected in parallel because it will
provide an additional termination. Therefore, buffering must be
provided before connecting a second monitor.
Since the RGB signals include ground as part of their dynamic
output range, it has previously been required to use a dual sup-
ply op amp to provide this buffering. In some systems this is the
only component that requires a negative supply so it can be
quite inconvenient to incorporate this multiple monitor feature.
Figure 40 shows a schematic of one channel of a single supply
gain-of-two buffer for driving a second RGB monitor. No cur-
rent is required when the amplifier output is at ground. The ter-
mination resistor at the monitor helps pull the output down at
low voltage levels.
6
4
7
3
2
AD8041
1k
75
10μF
+3V OR +5V
8
75
R, G OR B
NC
0.1μF
1k
PRIMARY RGB
MONITOR
75
SECOND RGB
MONITOR
Figure 40. Single Supply RGB Buffer
Figure 41 is an oscilloscope photo of the circuit in Figure 40
operating from a +3 V supply and driven by the Blue signal of a
color bar pattern. Note that the input and output are at ground
during the horizontal blanking interval. The RGB signals are
specified to output a maximum of 700 mV peak. The output of
the AD8041 is 1.4 V with the termination resistors providing a
divide-by-two. The Red and Green signals can be buffered in
the same manner with duplication of this circuit.
V
IN
GND
GND
V
OUT
10
0%
100
90
5μs
500mV
500mV
Figure 41. +3 V, RGB Buffer
Single Supply Composite Video Line Driver
Figure 42 shows a schematic of a single supply gain-of-two com-
posite video line driver. Since the sync tips of a composite video
signal extend below ground, the input must be ac coupled and
shifted positively to provide signal swing during these negative
excursions in a single supply configuration.
The input is terminated in 75
and ac coupled via C
IN
to a
voltage divider that provides the dc bias point to the input. Set-
ting the optimal bias point requires some understanding of the
nature of composite video signals and the video performance of
the AD8041.
Signals of bounded peak-to-peak amplitude that vary in duty
cycle require larger dynamic swing capability than their peak-to-
peak amplitude after ac coupling. As a worst case, the dynamic
signal swing required will approach twice the peak-to-peak
value. The two bounding cases are for a duty cycle that is mostly
low, but occasionally goes high at a fraction of a percent duty
cycle and vice versa.
Composite video is not quite this demanding. One bounding ex-
treme is for a signal that is mostly black for an entire frame, but
has a white (full intensity), minimum width spike at least once
per frame.
The other extreme is for a video signal that is full white every-
where. The blanking intervals and sync tips of such a signal will
have negative going excursions in compliance with composite
video specifications. The combination of horizontal and vertical
blanking intervals limit such a signal to being at its highest level
(white) for only about 75% of the time.
As a result of the duty cycle variations between the two extremes
presented above, a 1 V p-p composite video signal that is multi-
plied by a gain of two requires about 3.2 V p-p of dynamic volt-
age swing at the output for an op amp to pass a composite video
signal of arbitrary duty cycle without distortion.
Some circuits use a sync tip clamp along with ac coupling to
hold the sync tips at a relatively constant level in order to lower
the amount of dynamic signal swing required. However, these
circuits can have artifacts like sync tip compression unless they
are driven by sources with very low output impedance.
6
4
7
3
2
AD8041
R
F
1k
10k
10μF
+5V
75
COMPOSITE
VIDEO IN
NC
0.1μF
R
T
75
8
1000μF
0.1μF
4.99k
10μF
4.99k
47μF
R
G
1k
220μF
75
COAX
R
L
75
V
OUT
Figure 42. Single Supply Composite Video Line Driver
The AD8041 not only has ample signal swing capability to
handle the dynamic range required without using a sync tip
clamp, but also has good video specifications like differential
gain and differential phase when buffering these signals in an ac
coupled configuration.
相關PDF資料 |
PDF描述 |
|---|---|
| AD8041-EB | 160 MHz Rail-to-Rail Amplifier with Disable |
| AD8041AN | 160 MHz Rail-to-Rail Amplifier with Disable |
| AD8041AR | 160 MHz Rail-to-Rail Amplifier with Disable |
| AD8041ARZ-REEL | CMOS Low Cost, 10-Bit Multiplying DAC; Package: none available; No of Pins: 16; Temperature Range: Military |
| AD8042ARZ | Dual 160 MHz Rail-to-Rail Amplifier |
相關代理商/技術參數 |
參數描述 |
|---|---|
| AD8041-713Q | 制造商:Analog Devices 功能描述: |
| AD8041AN | 制造商:Analog Devices 功能描述:OP Amp Single Volt Fdbk R-R O/P 制造商:Rochester Electronics LLC 功能描述:100MHZ R-TO-R VLTG FDBK - Bulk 制造商:Analog Devices 功能描述:3V to 12V 1 170MHz IyAv 8PDIP Tube 制造商:Analog Devices 功能描述:AMPLIFIER IC NUMBER OF CIRCUITS:1 |
| AD8041ANZ | 功能描述:IC OPAMP VF R-R LP LDIST 8DIP RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標準包裝:1 系列:- 放大器類型:通用 電路數:4 輸出類型:滿擺幅 轉換速率:0.028 V/µs 增益帶寬積:105kHz -3db帶寬:- 電流 - 輸入偏壓:3nA 電壓 - 輸入偏移:100µV 電流 - 電源:3.3µA 電流 - 輸出 / 通道:12mA 電壓 - 電源，單路/雙路(±):2.7 V ~ 12 V，±1.35 V ~ 6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:14-TSSOP（0.173"，4.40mm 寬） 供應商設備封裝:14-TSSOP 包裝:剪切帶 (CT) 其它名稱:OP481GRUZ-REELCT |
| AD8041ANZ | 制造商:Analog Devices 功能描述:IC AMP VOLTAGE FEEDBACK |
| AD8041AR | 功能描述:IC OPAMP VF R-R LP LDIST 8SOIC RoHS:否 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標準包裝:73 系列:Over-The-Top® 放大器類型:通用 電路數:4 輸出類型:滿擺幅 轉換速率:0.07 V/µs 增益帶寬積:200kHz -3db帶寬:- 電流 - 輸入偏壓:1nA 電壓 - 輸入偏移:285µV 電流 - 電源:50µA 電流 - 輸出 / 通道:25mA 電壓 - 電源，單路/雙路(±):2 V ~ 44 V，±1 V ~ 22 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:16-WFDFN 裸露焊盤 供應商設備封裝:16-DFN-EP（5x3） 包裝:管件 |
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