# Ideal Semiconductor Switch

Ideal Semiconductor Switch

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• Simscape / Electrical / Semiconductors & Converters

## Description

The Ideal Semiconductor Switch block models an ideal semiconductor switching device.

The figure shows a typical i-v characteristic for an ideal semiconductor switch.

If the gate-cathode voltage exceeds the specified threshold voltage, the ideal semiconductor switch is in the on state. Otherwise the device is in the off state.

In the on state, the anode-cathode path behaves like a linear resistor with on-resistance Ron.

In the off state, the anode-cathode path behaves like a linear resistor with a low off-state conductance Goff.

Using the Integral Diode parameters, you can include an integral cathode-anode diode. An integral diode protects the semiconductor device by providing a conduction path for reverse current. An inductive load can produce a high reverse-voltage spike when the semiconductor device suddenly switches off the voltage supply to the load.

The table shows you how to set the Integral protection diode parameter based on your goals.

GoalValue to SelectBlock Behavior
Prioritize simulation speed.`Protection diode with no dynamics`The block includes an integral copy of the Diode block. To parameterize the internal Diode block, use the Protection parameters.
Precisely specify reverse-mode charge dynamics.`Protection diode with charge dynamics`The block includes an integral copy of the dynamic model of the Diode block. To parameterize the internal Diode block, use the Protection parameters.

## Ports

This figure shows the block port names.

### Conserving

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Port associated with the gate terminal. You can set the port to either a physical signal or electrical port.

Electrical conserving port associated with the anode terminal.

Electrical conserving port associated with the cathode terminal.

## Parameters

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### Main

Anode-cathode resistance when the device is on.

Anode-cathode conductance when the device is off. The value must be less than 1/R, where R is the value of On-state resistance.

Gate-cathode voltage threshold. The device turns on when the gate-cathode voltage is above this value.

### Integral Diode

Specify whether the block includes an integral protection diode. The default value is `None`.

If you want to include an integral protection diode, there are two options:

• ```Protection diode with no dynamics```

• ```Protection diode with charge dynamics```

Minimum voltage required across the `+` and `-` block ports for the gradient of the diode I-V characteristic to be 1/Ron, where Ron is the value of On resistance.

#### Dependencies

To enable this parameter, set Integral protection diode to ```Protection diode with no dynamics``` or ```Protection diode with charge dynamics```.

Rate of change of voltage versus current above the Forward voltage.

#### Dependencies

To enable this parameter, set Integral protection diode to ```Protection diode with no dynamics``` or ```Protection diode with charge dynamics```.

Conductance of the reverse-biased diode.

#### Dependencies

This parameter is visible only when the Integral protection diode parameter is set to `Protection diode with no dynamics` or ```Protection diode with charge dynamics```.

Diode junction capacitance.

#### Dependencies

This parameter is visible only when the Integral protection diode parameter is set to `Protection diode with charge dynamics`.

Initial forward current when measuring peak reverse current. This value must be greater than zero.

#### Dependencies

This parameter is visible only when the Integral protection diode parameter is set to `Protection diode with charge dynamics`.

Rate of change of current when measuring peak reverse current. This value must be less than zero.

#### Dependencies

This parameter is visible only when the Integral protection diode parameter is set to `Protection diode with charge dynamics`.

Determines how you specify reverse recovery time in the block. The default value is `Specify reverse recovery time directly`.

If you select `Specify stretch factor` or `Specify reverse recovery charge`, you specify a value that the block uses to derive the reverse recovery time. For more information on these options, see How the Block Calculates TM and Tau.

#### Dependencies

This parameter is visible only when the Integral protection diode parameter is set to `Protection diode with charge dynamics`.

Interval between the time when the current initially goes to zero (when the diode turns off) and the time when the current falls to less than 10% of the peak reverse current. The value of the Reverse recovery time, trr parameter must be greater than the value of the Peak reverse current, iRM parameter divided by the value of the Rate of change of current when measuring iRM parameter.

#### Dependencies

This parameter is visible only when the Integral protection diode parameter is set to `Protection diode with charge dynamics` and the Reverse recovery time parameterization parameter is set to `Specify reverse recovery time directly`.

Value that the block uses to calculate Reverse recovery time, trr. This value must be greater than `1`. Specifying the stretch factor is an easier way to parameterize the reverse recovery time than specifying the reverse recovery charge. The larger the value of the stretch factor, the longer it takes for the reverse recovery current to dissipate.

#### Dependencies

This parameter is visible only when the Integral protection diode parameter is set to `Protection diode with charge dynamics` and the Reverse recovery time parameterization parameter is set to `Specify stretch factor`.

Value that the block uses to calculate Reverse recovery time, trr. Use this parameter if the data sheet for your diode device specifies a value for the reverse recovery charge instead of a value for the reverse recovery time.

The reverse recovery charge is the total charge that continues to dissipate when the diode turns off. The value must be less than $-\frac{{i}^{2}{}_{RM}}{2a},$

where:

• iRM is the value specified for Peak reverse current, iRM.

• a is the value specified for Rate of change of current when measuring iRM.

#### Dependencies

This parameter is visible only when the Integral protection diode parameter is set to `Protection diode with charge dynamics` and the Reverse recovery time parameterization parameter is set to `Specify reverse recovery charge`.