SBOA362A December   2019  – October 2026 REF34 , REF34-Q1 , REF3425-EP , REF3430-EP , REF3433-EP , REF3440-EP , REF4132-Q1 , REF50 , REF5020-EP , REF5020A-Q1 , REF5025-EP , REF5025-HT , REF5025A-Q1 , REF5030A-Q1 , REF5040-EP , REF5040A-Q1 , REF5045A-Q1 , REF5050-EP , REF5050A-Q1 , REF50E , REF70

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Voltage Reference Architecture
    1. 2.1 Shunt or Series Reference
    2. 2.2 Choosing the Best System Reference
  6. 3Key Specifications for Voltage Reference
    1. 3.1 Temperature Coefficient
    2. 3.2 Initial Accuracy
    3. 3.3 0.1–10 Hz Peak-to-peak Noise
    4. 3.4 Thermal Hysteresis and Long-term Stability
    5. 3.5 Load and Line Regulation
  7. 4Method of Negative Output Design and Noise Analysis
    1. 4.1 Voltage Inverting by Level Shift using REF5025 and OPA192
    2. 4.2 Using a Buffer to Generate Negative Reference Output
    3. 4.3 A Way to Minimize the Noise
  8. 5Conclusion
  9. 6References
  10. 7Revision History

1 Introduction

In general, a voltage reference is an electronic device that produces a fixed voltage, regardless of the following:

  • Loading on the device
  • Power supply variations
  • Temperature changes
  • Passage of time

Voltage references are typically seen with the following devices and systems:

  • Analog-to-digital (ADC) converters
  • Digital-to-analog (DAC) converters
  • Power supplies
  • Other measurement systems

The REF50xx is a family of low-noise, low-drift, very high-precision voltage references. This document provides a comprehensive overview of voltage reference basics, application design, and negative reference output configuration. Voltage references are one of the key components in data conversion systems. They enable an ADC or DAC to read accurate values, and are used in various high-accuracy data converting applications. Modern active components, such as A/D and D/A converters and operational amplifiers, typically do not require a negative supply voltage. However, there are still some cases where a negative voltage is required, including high-performance, high-speed A/D and D/A converters. TI's low-noise analog front ends (AFEs) have a time-gain control feature that can alter the receiver gain as a function of time. These AFEs can support ultrasound scanner applications.