SIMPLIS Parts

SIMPLIS Zener Options

Zener Extracted Parameters
Test Condition	Default Value	Units	Description
SPICE Model	BZX79-4V7		The SPICE model used to extract SIMPLIS parameters.
Automatically copy ...	Checked		If checked, automatically copies the extracted parameters to the user-defined parameters.

Test current	5m	A	The peak forward and reverse current used for curve fitting. The algorithm fits a straight line between 50% and 100% of this value.
Model temperature	50	°C	Temperature used for all extraction simulations.
Number of Segments	3		Zener Diodes may have two segments - representing Zener Resistance and Off Resistance or three segments with the third segment representing the transition between the Zener and Off states.
Initial Condition	2 Off		Sets initial conducting segment.
Limit maximum off resistance	Checked	none	Limits the off resistance for the diode. For some SPICE models, this will produce a SIMPLIS model which runs faster.
Maximum off resistance	100Meg	W	The maximum off resistance of the diode. This value is used only if the "Limit maximum off resistance" checkbox is Checked.

Additional Options
Option	Default Value	Description
Initial Place Preference	Extracted	Indicates which model type (Extracted or User-defined) is selected when you place the device on the schematic.
Automatically copy extracted parameters to User-defined parameters	Checked	If checked the extracted parameters overwrite the user-defined parameters each time a model is extracted. If unchecked, the user-defined parameters are never overwritten.
Number of anti-parallel diode segments	3	Sets the number of segments for the Body diode extraction algorithm. If you select 2, the algorithm models on and off resistance. If you select 3, the algorithm models a transition resistance in between the on and off segments.
Debug
Output parameter ...	Unchecked	If checked, the debug statements are automatically written to the deck file. The Command shell menu SIMPLIS ▶ Edit Netlist (after preprocess) opens the .deck file for editing. An example set of debug statements can be found in the Deck-Level Debug section.
Advanced options	Hidden	Click this button to view or change the advanced options. For more information, see Advanced Options.

Deck-Level Debug

If you check "Output parameter debug statements to the deck file," each Zener in the design has a debug report inserted in the .deck file when you run a simulation. This debug report displays the calculated values for each major parameter in a formatted table. You can edit the .deck file with the Command shell menu SIMPLIS ▶ Edit Netlist (after preprocess). Two sample debug reports are shown below.

Single Zener diode model report

This debug report was taken from a single zener diode model. Notice the extracted breakdown voltage:

VD1 is approximately the same as the rated breakdown voltage.
The forward drop is represented by VD4.
The Zener Resistance is Segment #1.
The forward resistance is Segment #5.

***SIMPLIS DEBUG EXTRACTED ZENER START******************************************
***                                                                          ***
*** Device with REF : D2                                                     ***
***                                                                          ***
*** Extracted from SPICE model: BZX79-4V7                                    ***
***                                                                          ***
********************************************************************************
*
* Model Extraction Parameters
*
* IZ_TEST : 5m
* TEMP : 50
* NUMSEG : 3
* LIMIT_MAX_ROFF : 1
* MAX_ROFF : 100Meg
*
* Conduction Parameters
*
* NUMSEG : 5
* R SEG#1 : 11.6882
* R SEG#2 : 48.6399
* R SEG#3 : 7.29812Meg
* R SEG#4 : 82.5919
* R SEG#5 : 17.009
*
* Conduction V-I Points
*
* VD0 : -4.63624
* ID0 : -5m
* VD1 : -4.59431
* ID1 : -1.41263m
* VD2 : -4.52563
* ID2 : -620.109n
* VD3 : 402.344m
* ID3 : 55.1299n
* VD4 : 530.551m
* ID4 : 1.55235m
* VD5 : 589.192m
* ID5 : 5m
*
********************************************************************************
***                                                                          ***
*** Device with REF : D2                                                     ***
***                                                                          ***
*** Extracted from SPICE model: BZX79-4V7                                    ***
***                                                                          ***
***SIMPLIS DEBUG EXTRACTED ZENER END********************************************

Back-to-back zener diode model

This debug report was from a back-to-back zener diode model. Notice that ..

The resistance of the first and last segments are identical.
The V-I points are symmetric about the origin, with a single off resistance segment.
The breakdown resistances are higher than the single zener because the breakdown resistances include both a forward and zener resistance. The breakdown resistance is approximately equal to the sum of the forward and zener resistances in the single diode example.

***SIMPLIS DEBUG EXTRACTED ZENER START******************************************
***                                                                          ***
*** Device with REF : D3                                                     ***
***                                                                          ***
*** Extracted from SPICE model: BZX79-4V7                                    ***
***                                                                          ***
********************************************************************************
*
* Model Extraction Parameters
*
* IZ_TEST : 5m
* TEMP : 50
* NUMSEG : 3
* LIMIT_MAX_ROFF : 1
* MAX_ROFF : 100Meg
*
* Conduction Parameters
*
* NUMSEG : 5
* R SEG#1 : 28.6963
* R SEG#2 : 131.454
* R SEG#3 : 7.91203Meg
* R SEG#4 : 131.454
* R SEG#5 : 28.6963
*
* Conduction V-I Points
*
* VD0 : -5.22543
* ID0 : -5m
* VD1 : -5.12505
* ID1 : -1.50199m
* VD2 : -4.92769
* ID2 : -622.81n
* VD3 : 4.92769
* ID3 : 622.81n
* VD4 : 5.12505
* ID4 : 1.50199m
* VD5 : 5.22543
* ID5 : 5m
*
********************************************************************************
***                                                                          ***
*** Device with REF : D3                                                     ***
***                                                                          ***
*** Extracted from SPICE model: BZX79-4V7                                    ***
***                                                                          ***
***SIMPLIS DEBUG EXTRACTED ZENER END********************************************