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| 型号： | AD8045ARDZ |
| 厂商： | ANALOG DEVICES INC |
| 元件分类： | 运动控制电子 |
| 英文描述： | 3 nV/Hz Ultralow Distortion, High Speed Op Amp |
| 中文描述： | OP-AMP, 1000 uV OFFSET-MAX, PDSO8 |
| 封装： | MS-012, SOIC-8 |
| 文件页数： | 23/24页 |
| 文件大小： | 474K |
| 代理商： | AD8045ARDZ |
AD8045
EXPOSED PADDLE
The AD8045 features an exposed paddle, which lowers the
thermal resistance by 25% compared to a standard SOIC plastic
package. The exposed paddle of the AD8045 is internally con-
nected to the negative power supply pin. Therefore, when laying
out the board, the exposed paddle must either be connected to
the negative power supply or left floating (electrically isolated).
Soldering the exposed paddle to the negative power supply metal
ensures maximum thermal transfer. Figure 74 and Figure 75 show
the proper layout for connecting the SOIC and LFCSP exposed
paddle to the negative supply.
Rev. A | Page 23 of 24
0
Figure 74. SOIC Exposed Paddle Layout
The use of thermal vias or “heat pipes” can also be incorporated
into the design of the mounting pad for the exposed paddle.
These additional vias help to lower the overall theta junction to
ambient (θ
JA
). Using a heavier weight copper on the surface to
which the amplifier’s exposed paddle is soldered can greatly
reduce the overall thermal resistance “seen” by the AD8045.
0
Figure 75. LFCSP Exposed Paddle Layout
For existing designs that want to incorporate the AD8045,
electrically isolating the exposed paddle is another option. If the
exposed paddle is electrically isolated, the thermal dissipation is
primarily through the leads, and the thermal resistance of the
package now approaches 125°C/W, the standard SOIC θ
JA
.
However, a thermally conductive and electrically isolated pad
material may be used. A thermally conductive spacer, such as
the Bergquist Company’s Sil-Pad, is an excellent solution to this
problem. Figure 76 shows a typical implementation using
thermal pad material.
0
THERMAL CONDUCTIVE INSULATOR
Figure 76. SOIC with Thermal Conductive Pad Material
The thermal pad provides high thermal conductivity but
isolates the exposed paddle from ground or other potential. It is
recommended, when possible, to solder the paddle to the nega-
tive power supply plane or trace for maximum thermal transfer.
Note that soldering the paddle to ground shorts the negative
power supply to ground and can cause irreparable damage to
the AD8045.
DRIVING CAPACITIVE LOADS
In general, high speed amplifiers have a difficult time driving
capacitive loads. This is particularly true in low closed-loop
gains, where the phase margin is the lowest. The difficulty arises
because the load capacitance, C
L
, forms a pole with the output
resistance, R
O
, of the amplifier. The pole can be described by the
equation
L
O
P
C
R
f
2π
1
=
If this pole occurs too close to the unity gain crossover point,
the phase margin degrades. This is due to the additional phase
loss associated with the pole.
The AD8045 output can drive 18 pF of load capacitance directly,
in a gain of +2 with 30% overshoot, as shown in Figure 37.
Larger capacitance values can be driven but must use a snub-
bing resistor (R
SNUB
) at the output of the amplifier, as shown in
Figure 61 and Figure 62. Adding a small series resistor, R
SNUB
,
creates a zero that cancels the pole introduced by the load
capacitance. Typical values for R
SNUB
can range from 25 to
50 . The value is typically arrived at empirically and based on
the circuit requirements.
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| AD8045ARDZ-REEL | 3 nV/Hz Ultralow Distortion, High Speed Op Amp |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| AD8045ARDZ-REEL | 功能描述:IC OPAMP VF ULDIST LN 70MA 8SOIC RoHS:是 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 标准包装:1,000 系列:- 放大器类型:电压反馈 电路数:4 输出类型:满摆幅 转换速率:33 V/µs 增益带宽积:20MHz -3db带宽:30MHz 电流 - 输入偏压:2nA 电压 - 输入偏移:3000µV 电流 - 电源:2.5mA 电流 - 输出 / 通道:30mA 电压 - 电源，单路/双路(±):4.5 V ~ 16.5 V，±2.25 V ~ 8.25 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:14-SOIC（0.154"，3.90mm 宽） 供应商设备封装:14-SOIC 包装:带卷 (TR) |
| AD8045ARDZ-REEL7 | 功能描述:IC OPAMP VF ULDIST LN 70MA 8SOIC RoHS:是 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 标准包装:1,000 系列:- 放大器类型:电压反馈 电路数:4 输出类型:满摆幅 转换速率:33 V/µs 增益带宽积:20MHz -3db带宽:30MHz 电流 - 输入偏压:2nA 电压 - 输入偏移:3000µV 电流 - 电源:2.5mA 电流 - 输出 / 通道:30mA 电压 - 电源，单路/双路(±):4.5 V ~ 16.5 V，±2.25 V ~ 8.25 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:14-SOIC（0.154"，3.90mm 宽） 供应商设备封装:14-SOIC 包装:带卷 (TR) |
| AD8045AR-REEL7 | 制造商:Analog Devices 功能描述:ULTRA-LOW DISTORTION HIGH SPEED AMPLIFIER - Tape and Reel |
| AD8047 | 制造商:AD 制造商全称:Analog Devices 功能描述:250 MHz, General Purpose Voltage Feedback Op Amps |
| AD8047_03 | 制造商:AD 制造商全称:Analog Devices 功能描述:250 MHz, General Purpose Voltage Feedback Op Amps |
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