Programming instructions

Basic Components
Multisim Component Reference Guide 2-18 ni.com
2.5 SBREAK
This device is a voltage-controlled switch.
 To change the component’s parameters:
1. Double-click on the placed component and select the Value tab.
2. Change the following as desired:
•
On-state Voltage (VON) — voltage at which the switch turns on.
•
Off-state Voltage (VOFF) — voltage at which the switch turns off.
•
On-state Resistance (RON) — resistance of the device during its on-state.
•
Off-state Resistance (ROF) — resistance of the device during its off-state.
3. Click OK to save to close the dialog box.
2.6 Resistor
Resistors come in a variety of sizes, depending on the power they can safely dissipate. A
resistor’s resistance, R, is measured in ohms. Color-coded stripes on a real-world resistor
specify its resistance and tolerance. Larger resistors have this information printed on them.
Any electrical wire has resistance, depending on its material, diameter and length. Wires that
must conduct very heavy currents (for example, ground wires on lightning rods) have large
diameters to reduce resistance.
The power dissipated by a resistive circuit carrying electric current is in the form of heat.
Circuits dissipating excessive energy will literally burn up. Practical circuits must take power
capacity into account.
In Multisim, the Resistance, R, of a resistor instance is calculated using the following
equation:
R = Ro * { 1 + TC1*(T - To) + TC2*[(T-To)^2] }
where:
R = The resistance of the resistor
Ro = The resistance of the resistor at temperature To
To = Nominal temperature = 27 degrees C [CONSTANT]
TC1 = First order temperature coefficient
ComponentRef.book Page 18 Thursday, December 7, 2006 10:12 AM