MOSFET
Purpose
Ideal MOSFET with optional on-resistance
Library
Electrical / Power Semiconductors
Description
The Metal Oxide Semiconductor Field Effect Transistor is a semiconductor switch that is controlled via the external gate. It conducts a current from drain to source (or vice-versa) only if the gate signal is not zero.
Parameters
The following parameters may either be scalars or vectors corresponding to the implicit width of the component:
- On-resistance
The resistance \(R_{\mathrm{on}}\) of the conducting device, in ohms \((\Omega)\). The default is
0.- Initial conductivity
Initial conduction state of the MOSFET. The MOSFET is initially blocking if the parameter evaluates to zero, otherwise it is conducting.
- Thermal description
Switching losses, conduction losses and thermal equivalent circuit of the component. For more information see chapter Thermal Modeling. If no thermal description is given, the losses are calculated based on the voltage drop \(v_{\mathrm{on}} = R_{\mathrm{on}}\cdot i\).
- Thermal interface resistance
The thermal resistance of the interface material between case and heat sink, in \((\mathrm{K}/\mathrm{W})\). The default is
0.- Number of parallel devices
This parameter is used to simulate the effect of connecting multiple identical devices in parallel while adding only one single switch element to the electrical system equations. Other component parameters such as the Thermal description, the Thermal interface resistance and also the electrical On-resistance refer to the characteristics of an individual device, while the calculated losses and other probe signals refer to the sum over all devices.
If \(N_\mathrm{p}\) is the number of parallel devices, each device will conduct \(1/N_\mathrm{p}\) of the total current through the component, and the total component loss will be \(N_\mathrm{p}\) times the loss of an individual device. The effective electrical on-resistance and the effective thermal interface resistance of the component are also \(1/N_\mathrm{p}\) times the respective parameter values. The default is
1.Example Model
See the example model “Thermal Modelling with Parallel Devices”.
Find it in PLECS under Help > PLECS Documentation > List of Example Models.
- Initial temperature
This parameter is used only if the device has an internal thermal impedance and specifies the temperature of the thermal capacitance at the junction at simulation start. The temperatures of the other thermal capacitances are initialized based on a thermal “DC” analysis. If the parameter is left blank, all temperatures are initialized from the external temperature. See also Temperature Initialization.
Probe Signals
- MOSFET voltage
The voltage measured between drain and source.
- MOSFET current
The current through the MOSFET flowing from drain to source.
- MOSFET gate signal
The gate input signal of the MOSFET.
- MOSFET conductivity
Conduction state of the internal switch. The signal outputs \(0\) when the MOSFET is blocking, and \(1\) when it is conducting.
- MOSFET junction temperature
Temperature of the first thermal capacitor in the equivalent Cauer network.
- MOSFET conduction loss
Continuous thermal conduction losses in watts \((\mathrm{W})\). Only defined if the component is placed on a heat sink.
- MOSFET switching loss
Instantaneous thermal switching losses in joules \((\mathrm{J})\). Only defined if the component is placed on a heat sink.