SBOA640 May   2026 OPA455 , OPA462

 

  1.   1
  2.   Design Goals
  3.   Design Description
  4.   Design Notes
  5.   Design Steps
  6.   Design Simulation Results
  7.   Design Measured Results
  8.   Target Applications
  9.   Design Featured Devices
  10.   Design Alternative Devices
  11.   Design References
  12.   Additional Resources
  13.   Trademarks

Design Simulation Results

OPA462 Discrete Output Current Boost RZCO TINA CircuitOPA462 Discrete Output Current Boost RZCO TINA Circuit
Note: The SPICE model FDD5N60NZ was used for modeling as there is no model available for the 500V version of the NMOS. The characteristics are similar enough to provide a close approximation for simulation results.

TINA simulations are run originally without the voltage divider as part of the circuit. This allows for insight into the optimized value of RZCO. Later we will add a voltage divider to the circuit to further optimize crossover distortion.

Simulation Results for RZCO and Corresponding IZCO ValuesSimulation Results for RZCO and Corresponding IZCO Values

A 10VPP square wave is applied to the input of the circuit. The output response provides insight into the current driving the load when the MOSFETs are turned off. Selecting RZCO resistors that are too low (100 Ω, 499 Ω) result in excessive current flow (labelled I_ZCO) from the output of the amplifier. Here, 1kΩ was chosen for RZCO as it adds 5 mA of current to the circuit, as opposed to the 10 mA of current consumption with the 499Ω resistor (see Simulation Results for RZCO and Corresponding IZCO Values ). Furthermore, the noise difference between the 499Ω resistor and the 1kΩ resistor is minimal, making 1kΩ a preferred choice for RZCO. A larger resistor can be used but adds additional noise to the circuit.

Simulation Results for VOUT Distribution for RZCO = 1 kΩSimulation Results for VOUT Distribution for RZCO = 1 kΩ

The distortion is minimized with RZCO = 1kΩ, but there is still crossover distortion in the circuit. Adding a voltage divider to the circuit allows for further optimization, as seen in the OPA462 Discrete Output Boost TINA Circuit figure.

OPA462 Discrete Output Current Boost TINA CircuitOPA462 Discrete Output Current Boost TINA Circuit
OPA462 Discrete Output Current Boost Circuit Simulation ResultsOPA462 Discrete Output Current Boost Circuit Simulation Results

The voltage divider was added to the circuit and further minimizes cross over distortion on the output of the circuit. The post processor in TINA is used to calculate the average output power of the circuit. Additionally, the post processor is used to show the output power of the OPA462 is minimal, approximately 300mW (labeled DUT_POWER).