SLPS764 September   2024 RES60A-Q1

ADVANCE INFORMATION  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Ratiometric Matching
      2. 6.3.2 Ultra-Low Noise
    4. 6.4 Device Functional Modes
  8. 7 Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1 Battery Stack Measurement
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Development Support
        1. 8.1.1.1 PSpice® for TI
        2. 8.1.1.2 TINA-TI™ Simulation Software (Free Download)
        3. 8.1.1.3 TI Reference Designs
        4. 8.1.1.4 Analog Filter Designer
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

6.3.2 Ultra-Low Noise

Noise in resistors can be evaluated in two separate regions: low-frequency flicker noise and wideband thermal noise. Flicker, or 1/f noise, is extremely important for systems that require signal gain at frequencies less that 100Hz. The flicker noise for thin-film resistors, including the RES60A-Q1, is lower than that of thick-film resistor processes. Thermal noise typically dominates in the region greater than 1kHz, and increases as resistor magnitude increases. Noise is modeled as a voltage source in series with the resistor.

For a resistive divider such as the RES60A-Q1, the thermal noise as measured at the center tap of two resistors RHV and RLV is equivalent to the thermal noise of a resistor with value RHV || RLV:

Equation 6. e N = 4 k B T R

where:

  • eN is the thermal noise density in nV/√Hz
  • T is the absolute temperature in kelvins (K)
  • kB is the Boltzmann constant, 1.381 × 10-23 J/K
  • R = RHV || RLV

RHV >> RLV; therefore, R ≈ RLV. As an example, for the RES60A610-Q1:

Equation 7. e N = 4 k B T R = 4 × 1.38 E - 23 J K × 278 K × 12.5 M Ω   ∥   20.49 k Ω = 18 n V / H z