ZHCS968B June   2012  – November 2017 INA827

PRODUCTION DATA.  

  1. 1 特性
  2. 2 应用
  3. 3 说明
    1.     简化电路原理图
  4. 4 修订历史记录
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
  7. 7 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Setting the Gain
        1. 8.3.1.1 Gain Drift
      2. 8.3.2  Offset Trimming
      3. 8.3.3  Input Common-Mode Range
      4. 8.3.4  Inside the INA827
      5. 8.3.5  Input Protection
      6. 8.3.6  Input Bias Current Return Path
      7. 8.3.7  Reference Pin
      8. 8.3.8  Dynamic Performance
      9. 8.3.9  Operating Voltage
        1. 8.3.9.1 Low-Voltage Operation
      10. 8.3.10 Error Sources
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 CMRR vs Frequency
    2. 11.2 Layout Example
  12. 12器件和文档支持
    1. 12.1 文档支持
      1. 12.1.1 相关文档
    2. 12.2 接收文档更新通知
    3. 12.3 社区资源
    4. 12.4 商标
    5. 12.5 静电放电警告
    6. 12.6 Glossary
  13. 13机械、封装和可订购信息

封装选项

机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)
订购信息

9.2.2 Detailed Design Procedure

There are two modes of operation for the circuit shown in Figure 62: current input and voltage input. This design requires R1 >> R2 >> R3. Given this relationship, the current input mode transfer function is given by Equation 2.

Equation 2. INA827 q_curr_mode_xfer_function_bos562.gif

where

  • G represents the gain of the instrumentation amplifier

The transfer function for the voltage input mode is shown by Equation 3.

Equation 3. INA827 q_voltage_input_mode_xfer_function_bos562.gif

R1 sets the input impedance of the voltage input mode. The minimum typical input impedance is 100 kΩ. 100 kΩ is selected for R1 because increasing the R1 value also increases noise. The value of R3 must be extremely small compared to R1 and R2. 20 Ω for R3 is selected because that resistance value is much smaller than R1 and yields an input voltage of ±400 mV when operated in current mode (±20 mA).

Equation 4 can be used to calculate R2 given VD = ±400 mV, VIN = ±10 V, and R1 = 100 kΩ.

Equation 4. INA827 q_r2_vd_vin_r1_bos562.gif

The value obtained from Equation 4 is not a standard 0.1% value, so 4.12 kΩ is selected. R1 and R2 also use 0.1% tolerance resistors to minimize error.

The ideal gain of the instrumentation amplifier is calculated with Equation 5.

Equation 5. INA827 q_ideal_gain_bos562.gif

Using the INA827 gain equation, the gain-setting resistor value is calculated as shown by Equation 6.

Equation 6. INA827 q_gain_setting_value_ina827 rev.png

107 kΩ is a standard 0.1% resistor value that can be used in this design. Finally, the output RC filter components are selected to have a –3-dB cutoff frequency of 1 MHz.