SIMPLIS Zener Options
The default test conditions for the Extract Zener Parameters dialog can be set from the menu
| 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. |
| 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 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 . 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*******************************************