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Current-Controlled Switch - Model current-controlled switch with hysteresis

Library

Passive Devices

Description

The Current-Controlled Switch block represents the electrical characteristics of a switch whose state is controlled by the current through the input ports (the controlling current):

• When the controlling current is greater than the sum of the Threshold current, IT and Hysteresis current, IH parameter values, the switch is closed and has a resistance equal to the On resistance, RON parameter value.

• When the controlling current is less than the Threshold current, IT parameter value minus the Hysteresis current, IH parameter value, the switch is open and has a resistance equal to the Off resistance, ROFF parameter value.

• When the controlling current is greater than or less than the Threshold current, IT parameter value by an amount less than or equal to the Hysteresis current, IH parameter value, the current is in the crossover region and the state of the switch remains unchanged.

Basic Assumptions and Limitations

The block output resistance model is discontinuous during switching. The discontinuity might cause numerical issues. Try the following actions to resolve the issues:

• Set the On resistance, RON and Off resistance, ROFF parameter values to keep the ratio RON/ROFF as small as possible, and less than 1e+12.

• Increase the Hysteresis current, IH parameter value to reduce switch chatter.

• Decrease the Max step size parameter value (in the Configuration Parameters block dialog box).

  Note   This increases the simulation time.

Dialog Box and Parameters

Threshold current, IT

The current above which the block interprets the controlling current as HIGH. The default value is 0 A.

Note   The controlling current must differ from the threshold current by at least the Hysteresis current, IH parameter value to change the state of the switch.

Hysteresis current, IH

The amount by which the controlling current must exceed or fall below the Threshold current, IT parameter value to change the state of the switch. The default value is 0 A.

On resistance, RON

The resistance of the switch when it is closed. The default value is 1 Ω.

Off resistance, ROFF

The resistance of the switch when it is open. The default value is 1e+12 Ω.

Initial switch state

Select one of the following options for the state of the switch at the start of the simulation:

• On — The switch is initially closed and its resistance value is equal to the On resistance, RON parameter value. This is the default option.

• Off — The switch is initially open and its resistance value is equal to the Off resistance, ROFF parameter value.

Ports

The block has the following ports:

+

Positive electrical input and output ports.

-

Negative electrical input and output ports.

Crystal

DC Current Source

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