ZHCSN30C December   2020  – March 2022 LMP7704-SP

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 Pin Configuration and 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: VS = 5 V
    6. 6.6 Electrical Characteristics: VS = 10 V
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Radiation Hardened Performance
      2. 7.3.2 Engineering Model (Devices With /EM Suffix)
      3. 7.3.3 Capacitive Load
      4. 7.3.4 Input Capacitance
      5. 7.3.5 Diodes Between the Inputs
    4. 7.4 Device Functional Modes
      1. 7.4.1 Precision Current Source
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Low Input Voltage Noise
      2. 8.1.2 Total Noise Contribution
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 接收文档更新通知
    2. 11.2 支持资源
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 术语表
  12. 12Mechanical, Packaging, and Orderable Information

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8.1.2 Total Noise Contribution

The LMP7704-SP has a very-low input bias current, very-low input current noise, and very-low input voltage noise. As a result, this amplifier is an excellent choice for circuits with high-impedance sensor applications.

Figure 8-2 shows the typical input noise of the LMP7704-SP as a function of source resistance where:

  • en denotes the input-referred voltage noise.
  • ei is the voltage drop across source resistance due to input-referred current noise or ei = RS * in.
  • et shows the thermal noise of the source resistance.
  • eni shows the total noise on the input, where:
    GUID-29559F08-A62E-4101-B2F4-6B9CF7137C0D-low.gif
GUID-E57F4054-C273-473A-AF87-0C52A3321640-low.gif Figure 8-2 Total Input Noise

The input current noise of the LMP7704-SP is so low that this noise does not become the dominant factor in the total noise unless the source resistance exceeds 300 MΩ, which is an unrealistically high value.

As is evident in Figure 8-2, at lower RS values, total noise is dominated by the amplifier input voltage noise. If RS is larger than a few kilo-ohms, then the dominant noise factor becomes the thermal noise of RS. As mentioned previously, the current noise will not be the dominant noise factor for any practical application.