Parameterized Opto Coupler (Version 8.0+)

The Parameterized Opto Coupler models a opto coupler with a one or two pole frequency response, output transistor saturation characteristics, and photo diode forward voltage drop characteristics.

In this topic:

Model Name: Parameterized Opto Coupler (Version 8.0+)
Simulator: This device is compatible with the SIMPLIS simulator
Parts Selector Menu Location: Analog Functions > Parameterized Opto Coupler (Version 8.0+) Analog Functions | Parameterized Opto Coupler (Version 8.0+)
Symbol Library: simplis_analog_functions.sxslb
Model File: simplis_analog_functions.lb
Symbol Name: SIMPLIS_PARAM_OPTO
Subcircuit Name: SIMPLIS_PARAM_OPTO
Symbol:
Multiple Selections: Multiple devices can be selected and edited simultaneously.

Previous Version Compatibility

This symbol and the electrical model was introduced with version 8.0 and will not simulate in releases prior to Version 8.0.

For a opto coupler version compatible with versions prior to version 7.20, download the schematic component simplis_074_opto_for_versions_prior_to_8p0.sxcmp. Although not identical to this model, the optocoupler schematic component incorporates many of the features of this model.

Symbol Migration

Symbols placed on schematics in previous versions of SIMetrix/SIMPLIS can be automatically migrated to use the new symbols. The schematic tools menu Tools > Migrate Schematic Symbols to Version 8.20 will invoke a routine which migrates the existing symbols to the new symbols. As this action makes substantial changes to the schematic, it is recommended that you save a backup copy of the schematic first.

Editing the Parameterized Opto Coupler

To configure the Parameterized Opto Coupler, follow these steps:

  1. Double click the symbol on the schematic to open the editing dialog.
  2. Make the appropriate changes to the fields described in the table below the image.
Parameter Label Units Description
Current transfer ratio A/A The current transfer ratio of the opto coupler.
1st pole frequency Hz The opto coupler model allows you to define two poles in the transfer function.
This is the first pole frequency. You can set this to 0 to remove the pole from the model.
Use 2nd pole?   Inserts a second pole into the model
2nd pole frequency Hz The opto coupler model allow you to define two poles in the transfer function.

This is the second pole frequency and is only used if the Use 2nd pole? checkbox is selected.
Forward voltage V The photo diode forward voltage.
Forward resistance Ω The photo diode forward resistance in Ohms.

The diode is modeled with a two-segment PWL resistor this is the resistance of the conducting segment.
Saturation voltage V The output transistor saturation voltage.
On resistance Ω The on resistance of the opto coupler output transistor.
Output capacitance F The collector to emitter capacitance of the opto coupler output transistor.

Set to 0 to remove the capacitor from the circuit.

Example - DC Transfer Characteristics

The DC transfer characteristics can be verified with this test circuit : simplis_074_opto_dc_transfer.sxsch .

Waveforms - Transfer Characteristics

  • The waveforms shown below are for a test circuit with the following opto coupler parameters:
    • Current transfer ratio of 1 V/V (0dB)
    • Transistor saturation voltage of 400mV

Waveforms - Saturation Characteristics

The waveforms shown below are for a test circuit with the following opto coupler parameters:

  • Diode forward resistance of 100mΩ
  • Transistor saturation voltage of 500mV
  • Diode forward resistance of 10Ω

Example - Frequency Response

The test circuit used to generate the waveform examples in the next section can be downloaded here: simplis_074_opto_single_pole_freq_response.sxsch.

Waveforms - Single Pole

The waveforms shown below are for a test circuit with the following opto coupler parameters:

  • Single pole
  • 10kHz pole frequency
  • Current transfer ratio of 2 V/V (6dB)

Waveforms - Two Poles

 The waveforms shown below are for a test circuit with the following opto coupler parameters:

  • Two poles
  • 1kHz and 100kHz pole frequencies
  • Current transfer ratio of 2 V/V (6dB)