SLEWRATER - Slew Rate (Differential IO)
Model Kind
General
Model Sub-Kind
Generic Editor
SPICE Prefix
A
Model Name
SLEW
SPICE Netlist Template Format
@DESIGNATOR %%vd(%1,%2) %%vd(%3,%4) @"DESIGNATOR"SLEW
.MODEL @"DESIGNATOR"SLEW slew (?rise_slope|rise_slope=@rise_slope| ?fall_slope|fall_slope=@fall_slope|)
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.
| Rise_Slope | maximum rising slope value (Default = 1.0e9). |
| Fall_Slope | maximum falling slope value (Default = 1.0e9). |
Notes
This model provides a simple slew rate feature that limits the absolute rising and falling slope of the output, with respect to time, to a defined value.
The values for the Rise_Slope and Fall_Slope parameters are specified in units of Vs-1 or As-1. For example, to enter a slew rate of 0.05V/us, the entry would be 0.5e7.
The function will raise or lower the output value until the difference between the input and output is zero. It will then follow the input until the rise or fall slope limits are again exceeded.
The input signal can be either a differential current or differential voltage signal.
Examples
Consider the slew rate function in the above image, with the following characteristics:
- Pin1 (positive input) is connected to net
In1 - Pin2 (negative input) is connected to net
GND - Pin3 (positive output) is connected to net
Out - Pin4 (negative output) is connected to net
GND - Designator is
U2 - Rise_Slope =
2e7 - Fall_Slope =
2e7
The entry in the SPICE netlist would be:
*Schematic Netlist:
AU2 %vd(IN1,0) %vd(OUT,0) AU2SLEW
.MODEL AU2SLEW slew (rise_slope=2e7 fall_slope=2e7)
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
100.0u - Transient Step Time - set to
20.00n - Transient Max Step Time - set to
20.00n