SCDA060 May   2025 CD4053B

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 Demultiplexing Application Example in Solar System
    2. 1.2 Application Issue of Unwanted Voltage at OFF Channels
  5. 2OFF Channel Model Analysis
    1. 2.1 Channel Structure
    2. 2.2 Equivalent Resistor Model
  6. 3Fix OFF Channel Output Voltage to Ground
    1. 3.1 Pull-down Resistor
    2. 3.2 Pull-down Capacitor
    3. 3.3 Bleeder Resistor With a Switch
  7. 4Test and Measurement
    1. 4.1 Measurement Considerations
    2. 4.2 Test Result
  8. 5Summary
  9. 6References

5 Summary

The bidirectional operation characteristic of signal path enables analog multiplexer to support both multiplexer and demultiplexer usage. In demultiplexer application, when the OFF channel is directly connected to loads with large resistance like op amps, unwanted voltage signal can appear at the OFF-channel output and can be conveyed to the proceeding processor. This application note analyzes the problem by building an equivalent resistor model for OFF channel and proposes three designs to tackle. Since the scenario is sensitive to the input resistance of test equipment, measurement tips are also provided to avoid voltage reading mistakes.