SBOA418 july   2023 OPA2197-Q1 , OPA392

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction: Open-Loop Output Impedance (RO)
  5. 2Overview: Closed-Loop Amplifier Stability
  6. 3Example, Calculate Optimal Isolation Resistance to Drive Large Load Capacitance
  7. 4RO, RISO, and Capacitive Load Drive
  8. 5Derive Equation for Optimal Isolation Resistance
  9. 6Summary
  10. 7References

Abstract

This application note describes how an amplifier’s open-loop output impedance can be used to calculate an optimal isolation resistance for driving large capacitive loads. An example calculation is applied to select a resistor value to stabilize an amplifier that is oscillating due to a large capacitance at the output. The relationship between open-loop output impedance and capacitive load-drive is explored, and an equation is derived to quickly determine an optimal isolation resistance.