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参数资料
| 型号： | AD818AR |
| 厂商： | ANALOG DEVICES INC |
| 元件分类： | 音频／视频放大 |
| 英文描述： | Low Cost, Low Power Video Op Amp |
| 中文描述： | 1 CHANNEL, VIDEO AMPLIFIER, PDSO8 |
| 封装： | PLASTIC, SOIC-8 |
| 文件页数： | 10/12页 |
| 文件大小： | 353K |
| 代理商： | AD818AR |
AD818
REV. B
–10–
–
IN
+IN
NULL 1
NULL 8
OUTPUT
+V
S
–
V
S
Figure 34. AD818 Simplified Schematic
THEORY OF OPERATION
The AD818 is a low cost, video operational amplifier designed
to excel in high performance, high output current video
applications.
The AD818 (Figure 34) consists of a degenerated NPN differ-
ential pair driving matched PNPs in a folded-cascode gain stage.
The output buffer stage employs emitter followers in a class AB
amplifier which delivers the necessary current to the load, while
maintaining low levels of distortion.
The AD818 will drive terminated cables and capacitive loads of
10 pF or less. As the closed-loop gain is increased, the AD818
will drive heavier cap loads without oscillating.
INPUT CONSIDERATIONS
An input protection resistor (R
IN
in Figure 28) is required in
circuits where the input to the AD818 will be subjected to tran-
sient of continuous overload voltages exceeding the
±
6 V maxi-
mum differential limit. This resistor provides protection for the
input transistors by limiting their maximum base current.
For high performance circuits, it is recommended that a “bal-
ancing” resistor be used to reduce the offset errors caused by
bias current flowing through the input and feedback resistors.
The balancing resistor equals the parallel combination of R
IN
and R
F
and thus provides a matched impedance at each input
terminal. The offset voltage error will then be reduced by more
than an order of magnitude.
GROUNDING AND BYPASSING
When designing high frequency circuits, some special precau-
tions are in order. Circuits must be built with short interconnect
leads. When wiring components, care should be taken to pro-
vide a low resistance, low inductance path to ground. Sockets
should be avoided, since their increased interlead capacitance
can degrade circuit bandwidth.
Feedback resistors should be of low enough value (
≤
1 k
) to
assure that the time constant formed with the inherent stray
capacitance at the amplifier’s summing junction will not limit
performance. This parasitic capacitance, along with the parallel
resistance of R
F
/R
IN
, form a pole in the loop transmission which
may result in peaking. A small capacitance (1–5 pF) may be
used in parallel with the feedback resistor to neutralize this
effect.
Power supply leads should be bypassed to ground as close as
possible to the amplifier pins. Ceramic disc capacitors of
0.1
μ
F are recommended.
10k
1
7
6
8
4
3
2
–
V
S
V
OS
ADJUST
+V
S
AD818
Figure 35. Offset Null Configuration
OFFSET NULLING
The input offset voltage of the AD818 is inherently very low.
However, if additional nulling is required, the circuit shown in
Figure 35 can be used. The null range of the AD818 in this
configuration is
±
10 mV.
SINGLE SUPPLY OPERATION
Another exciting feature of the AD818 is its ability to perform
well in a single supply configuration. The AD818 is ideally
suited for applications that require low power dissipation and
high output current.
Referring to Figure 36, careful consideration should be given to
the proper selection of component values. The choices for
this particular circuit are: R1 + R3 R2 combine with C1 to
form a low frequency corner of approximately 10 kHz. C4 was
inserted in series with R4 to maintain amplifier stability at high
frequency.
Combining R3 with C2 forms a low pass filter with a corner
frequency of approximately 500 Hz. This is needed to maintain
amplifier PSRR, since the supply is connected to V
IN
through
the input divider. The values for R2 and C2 were chosen to
demonstrate the AD818’s exceptional output drive capability. In
this configuration, the output is centered around 2.5 V. In order
to eliminate the static dc current associated with this level, C3
was inserted in series with R
L
.
R2
3.3k
R1
3.3k
R3
100
C2
3.3 F
V
IN
C1
0.01 F
C4
0.001 F
R4
1k
3
2
AD818
V
OUT
+V
S
7
3.3 F
0.01 F
4
SELECT C1, R1, R2
FOR DESIRED LOW
FREQUENCY CORNER.
6
C3
0.1 F
R
L
150
1k
Figure 36. Single Supply Amplifier Configuration
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相关代理商/技术参数 |
参数描述 |
|---|---|
| AD818AR-EBZ | 功能描述:BOARD EVAL FOR AD818AR RoHS:是 类别:编程器，开发系统 >> 评估演示板和套件 系列:* 标准包装:1 系列:- 主要目的:电信，线路接口单元（LIU） 嵌入式:- 已用 IC / 零件:IDT82V2081 主要属性:T1/J1/E1 LIU 次要属性:- 已供物品:板，电源，线缆，CD 其它名称:82EBV2081 |
| AD818AR-REEL | 制造商:Analog Devices 功能描述:OP Amp Single Volt Fdbk 制造商:Analog Devices 功能描述:OP Amp Single Volt Fdbk ±18V/36V 8-Pin SOIC N T/R 制造商:Rochester Electronics LLC 功能描述:HI SPD, LOW PWR VIDEO AMP - Tape and Reel |
| AD818AR-REEL7 | 功能描述:IC VIDEO OPAMP LP 8-SOIC RoHS:否 类别:集成电路 (IC) >> 线性 - 放大器 - 视频放大器和频缓冲器 系列:- 标准包装:1,000 系列:- 应用:驱动器 输出类型:差分 电路数:3 -3db带宽:350MHz 转换速率:1000 V/µs 电流 - 电源:14.5mA 电流 - 输出 / 通道:60mA 电压 - 电源，单路/双路(±):5 V ~ 12 V，±2.5 V ~ 6 V 安装类型:表面贴装 封装/外壳:20-VFQFN 裸露焊盘 供应商设备封装:20-QFN 裸露焊盘（4x4） 包装:带卷 (TR) |
| AD818ARZ | 功能描述:IC VIDEO OPAMP LP 8-SOIC RoHS:是 类别:集成电路 (IC) >> 线性 - 放大器 - 视频放大器和频缓冲器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:50 系列:- 应用:TFT-LCD 面板：VCOM 驱动器 输出类型:满摆幅 电路数:1 -3db带宽:35MHz 转换速率:40 V/µs 电流 - 电源:3.7mA 电流 - 输出 / 通道:1.3A 电压 - 电源，单路/双路(±):9 V ~ 20 V，±4.5 V ~ 10 V 安装类型:表面贴装 封装/外壳:8-TSSOP，8-MSOP（0.118"，3.00mm 宽）裸露焊盘 供应商设备封装:8-uMax-EP 包装:管件 |
| AD818ARZ-REEL | 功能描述:IC VIDEO OPAMP LP 8-SOIC T/R RoHS:是 类别:集成电路 (IC) >> 线性 - 放大器 - 视频放大器和频缓冲器 系列:- 标准包装:1,000 系列:- 应用:驱动器 输出类型:差分 电路数:3 -3db带宽:350MHz 转换速率:1000 V/µs 电流 - 电源:14.5mA 电流 - 输出 / 通道:60mA 电压 - 电源，单路/双路(±):5 V ~ 12 V，±2.5 V ~ 6 V 安装类型:表面贴装 封装/外壳:20-VFQFN 裸露焊盘 供应商设备封装:20-QFN 裸露焊盘（4x4） 包装:带卷 (TR) |
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