HYSTERESIS - Hysteresis (Single-Ended IO)
Model Kind
General
Model Sub-Kind
Generic Editor
SPICE Prefix
A
Model Name
HYST
SPICE Netlist Template Format
@DESIGNATOR %1 %2 @"DESIGNATOR"HYST
.MODEL @"DESIGNATOR"HYST hyst (?in_low|in_low=@in_low| ?in_high|in_high=@in_high| ?hyst|hyst=@hyst| ?out_lower_limit|out_lower_limit=@out_lower_limit| ?out_upper_limit|out_upper_limit=@out_upper_limit| ?input_domain|input_domain=@input_domain| ?fraction|fraction=@fraction|)
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.
| In_Low | input low value (Default = 0). |
| In_High | input high value (Default = 1). |
| Hyst | hysteresis. The value entered must be a positive real number (Default = 0.1). |
| Out_Lower_Limit | output lower limit (Default = 0). |
| Out_Upper_Limit | output upper limit (Default = 1). |
| Input_Domain | input smoothing domain (Default = 0.01). |
| Fraction | used to control whether the smoothing domain is specified as a fractional (TRUE) or absolute (FALSE) value. (Default = TRUE). |
Notes
This is a simple buffer stage, providing hysteresis of the output with respect to the input. The input points about which the hysteresis effect operates is determined by the values assigned to the In_Low and In_High parameters.
The output is limited by the specification of the Out_Lower_Limit and Out_Upper_Limit parameters.
The points at which the hysteresis slope would normally change abruptly are defined as:
In_Low + Hyst and In_High + Hyst for input transition from low to high.
In_Low - Hyst and In_High - Hyst for input transition from high to low.
Use of the Input_Domain parameter, with a positive value, ensures that the hysteresis slope never changes abruptly, but is rather smoothed over the specified domain (the region prior to the hysteresis slope meeting the defined limit level).
The input signal can be either a single-ended current or single-ended voltage signal.
Examples
Consider the hysteresis function in the above image, with the following characteristics:
- Pin1 (input) is connected to net
In - Pin2 (output) is connected to net
Out - Designator is
U1 - In_Low =
-5V - In_High =
5V - Out_Lower_Limit =
-8V - Out_Upper_Limit =
8V - All other model parameters are left at their inherent defaults.
The entry in the SPICE netlist would be:
*Schematic Netlist:
AU1 IN OUT AU1HYST
.MODEL AU1HYST hyst (in_low=-5 in_high=5 out_lower_limit=-8 out_upper_limit=8 )
The effect of the function can be seen in the resultant waveforms obtained by running a transient analysis of the circuit.
In this example, the following analysis parameters on the Transient/Fourier Analysis page of the Analyses Setup dialog have been used:
- Transient Start Time - set to
0.000 - Transient Stop Time - set to
50.00m - Transient Step Time - set to
200.0u - Transient Max Step Time - set to
200.0u