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AD8601ARTZ-REEL7 参数 Datasheet PDF下载

AD8601ARTZ-REEL7图片预览
型号: AD8601ARTZ-REEL7
PDF下载: 下载PDF文件 查看货源
内容描述: 精密CMOS单电源,轨到轨输入/输出宽带运算放大器 [Precision CMOS, Single-Supply, Rail-to-Rail, Input/Output Wideband Operational Amplifiers]
分类和应用: 运算放大器放大器电路光电二极管PC
文件页数/大小: 24 页 / 356 K
品牌: ADI [ ADI ]
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AD8601/AD8602/AD8604  
THEORY OF OPERATION  
The AD8601/AD8602/AD8604 family of amplifiers are rail-to-rail  
input and output, precision CMOS amplifiers that operate from  
2.7 V to 5.0 V of the power supply voltage. These amplifiers use  
Analog Devices, Inc., DigiTrim® technology to achieve a higher  
degree of precision than available from most CMOS amplifiers.  
DigiTrim technology is a method of trimming the offset voltage  
of the amplifier after it has been assembled. The advantage in post-  
package trimming lies in the fact that it corrects any offset voltages  
due to the mechanical stresses of assembly. This technology is  
scalable and used with every package option, including the 5-lead  
SOT-23, providing lower offset voltages than previously achieved in  
these small packages.  
The NMOS and PMOS input stages are separately trimmed using  
DigiTrim to minimize the offset voltage in both differential pairs.  
Both NMOS and PMOS input differential pairs are active in a  
500 mV transition region, when the input common-mode voltage  
is between approximately 1.5 V and 1 V below the positive supply  
voltage. The input offset voltage shifts slightly in this transition  
region, as shown in Figure 9 and Figure 10 .The common-mode  
rejection ratio is also slightly lower when the input common-  
mode voltage is within this transition band. Compared to the  
Burr-Brown OPA2340UR rail-to-rail input amplifier, shown in  
Figure 54, the AD860x, shown in Figure 55, exhibits lower  
offset voltage shift across the entire input common-mode  
range, including the transition region.  
The DigiTrim process is completed at the factory and does not  
add additional pins to the amplifier. All AD860x amplifiers are  
available in standard op amp pinouts, making DigiTrim completely  
transparent to the user. The AD860x can be used in any precision  
op amp application.  
0.7  
0.4  
0.1  
The input stage of the amplifier is a true rail-to-rail architecture,  
allowing the input common-mode voltage range of the op amp  
to extend to both positive and negative supply rails. The voltage  
swing of the output stage is also rail-to-rail and is achieved by  
using an NMOS and PMOS transistor pair connected in a  
common-source configuration. The maximum output voltage  
swing is proportional to the output current, and larger currents  
limit how close the output voltage can get to the supply rail,  
which is a characteristic of all rail-to-rail output amplifiers.  
With 1 mA of output current, the output voltage can reach  
within 20 mV of the positive rail and within 15 mV of the  
negative rail. At light loads of >100 kΩ, the output swings  
within ~1 mV of the supplies.  
–0.2  
–0.5  
–0.8  
–1.1  
–1.4  
0
1
2
3
4
5
V
(V)  
CM  
Figure 54. Burr-Brown OPA2340UR Input Offset Voltage vs.  
Common-Mode Voltage, 24 SOIC Units @ 25°C  
0.7  
0.4  
0.1  
The open-loop gain of the AD860x is 80 dB, typical, with a load  
of 2 kΩ. Because of the rail-to-rail output configuration, the gain  
of the output stage and the open-loop gain of the amplifier are  
dependent on the load resistance. Open-loop gain decreases with  
smaller load resistances. Again, this is a characteristic inherent  
to all rail-to-rail output amplifiers.  
–0.2  
–0.5  
–0.8  
–1.1  
RAIL-TO-RAIL INPUT STAGE  
The input common-mode voltage range of the AD860x extends  
to both the positive and negative supply voltages. This maximizes  
the usable voltage range of the amplifier, an important feature  
for single-supply and low voltage applications. This rail-to-rail  
input range is achieved by using two input differential pairs, one  
NMOS and one PMOS, placed in parallel. The NMOS pair is  
active at the upper end of the common-mode voltage range, and  
the PMOS pair is active at the lower end.  
–1.4  
0
1
2
3
4
5
V
(V)  
CM  
Figure 55. AD8602AR Input Offset Voltage vs. Common-Mode Voltage,  
300 SOIC Units @ 25°C  
Rev. G | Page 15 of 24