SNOSDB6C December   2020  – March 2022 LMP7704-SP

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  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 Receiving Notification of Documentation Updates
    2. 11.2 Support Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.1.1 Low Input Voltage Noise

The LMP7704-SP has a very low input voltage noise of 9 nV/√Hz. This input voltage noise is further reduced by placing N amplifiers in parallel, as shown in Figure 8-1. The total voltage noise on the output of this circuit is divided by the square root of the number of amplifiers used in this parallel combination. The reason is because each individual amplifier acts as an independent noise source, and the average noise of independent sources is the quadrature sum of the independent sources divided by the number of sources. For N identical amplifiers:

Equation 6. GUID-5EC4A185-DCB4-4620-A405-AC339EABCCA9-low.gif

Figure 8-1 shows a schematic of this input voltage noise reduction circuit. Typical resistor values are:

RG = 10 Ω, RF = 1 kΩ, and RO = 1 kΩ.

GUID-57D81B68-2025-4E1E-8895-67932083B85B-low.gifFigure 8-1 Noise Reduction Circuit