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

2.2 Choosing the Best System Reference

Table 2-1 describes the advantages and disadvantages of each architecture.

Table 2-1 Series Versus Shunt Architecture
SERIES REFERENCESHUNT REFERENCE
ADVANTAGES
  • Significantly lower power dissipation
  • Generally higher precision
  • Low IQ and low drop out
  • Wide VIN tolerance with proper resistor selection
  • Can create negative, or floating, reference voltage
  • Inherent current sinking
DISADVANTAGES
  • Limited max VIN
  • VIN current fixed at max load
  • No shutdown mode
APPLICATIONS
  • Medical
  • Factory automation
  • Grid
  • Test equipment
  • Isolated power supplies
  • Automotive adapters