Fuse

Model Kind

General

Model Sub-Kind

Spice Subcircuit

SPICE Prefix

X

SPICE Netlist Template Format

@DESIGNATOR %1 %2 @MODEL #|PARAMS:| ?RESISTANCE|RESISTANCE=@RESISTANCE| ?CURRENT|CURRENT=@CURRENT|

Parameters (definable at component level)

The following component-level parameters are definable for this model type and are listed on the Parameters tab of the Sim Model dialog. To access this dialog, simply double-click on the entry for the simulation model link in the Models region of the Component Properties dialog.

Notes

A fuse is not one of the built-in SPICE engine models. It is a complex device and, as such, is defined using the hierarchical sub-circuit syntax.

All of the parameters will normally have a default value assigned. The default should be applicable to most simulations. Generally you do not need to change this value. Entering a value for a parameter on the Parameters tab of the Sim Model dialog will override its specified value in the sub-circuit file.

To check the default values of a fuse, open the appropriate sub-circuit (.ckt) file. You can view the content of this file for the model specified on the Model Kind tab of the Sim Model dialog, by clicking on the Model File tab at the bottom of the dialog. The default parameter values are listed in the .SUBCKT line.

Examples

Consider the fuse in the above image, with the following characteristics:

• Pin1 is connected to net In
• Pin2 is connected to net Out
• Designator is F1
• The linked simulation sub-circuit file is FUSE.ckt, with the following content:

*FUSE:Fuse Subcircuit Parameters
*CURRENT    = Fuse current
*RESISTANCE = Inernal resistance
.SUBCKT FUSE 1 2 PARAMS: CURRENT=1 RESISTANCE=1m
SW1 1 2 3 0 SMOD OFF
BNLV 3 0 V=(abs(v(1,2)))
.MODEL SMOD SW (VT={(CURRENT*RESISTANCE)} RON=1g ROFF={RESISTANCE})
.ENDS FUSE 

• CURRENT = 500mA - set on the Parameters tab of the Sim Model dialog.

The entries in the SPICE netlist would be:

*Schematic Netlist:
XF1 IN OUT FUSE PARAMS:  CURRENT=500mA
.
.
*Models and Subcircuit:
.SUBCKT FUSE 1 2 PARAMS: CURRENT=1 RESISTANCE=1m
SW1 1 2 3 0 SMOD OFF
BNLV 3 0 V=(abs(v(1,2)))
.MODEL SMOD SW (VT={(CURRENT*RESISTANCE)} RON=1g ROFF={RESISTANCE})
.ENDS FUSE

The Netlister will evaluate the formulae in the sub-circuit definition using the value for the CURRENT parameter specified in the Sim Model dialog (which overrides the default) and the default value for the RESISTANCE parameter (1 mOhm), as defined in the FUSE.ckt file.