Exponential Current Source

R2026b

Exponential pulse current source

• 

Exponential Current Source block

To add a block to a model, double-click the canvas and start typing the block name. Then, select the block from the list.

Libraries:
Simscape / Electrical / Additional Components / SPICE Sources

Description

The Exponential Current Source block represents a current source whose output current value is an exponential pulse as a function of time and is independent of the voltage across the terminals of the source. The following equations describe the current through the source as a function of time:

$$\begin{array}{l}{I}_{out}\left(0\le Time\le TDR\right))=I1\\ I_{out}\left(TDR<Time\le TDF\right)=I1+\left(I2-I1\right)*\left(1-e^{-(Time-TDR)/TR}\right)\\ I_{out}\left(TDF<Time\right)=I1+\left(I2-I1\right)*\left(e^{-(Time-TDF)/TF}-e^{-(Time-TDR)/TR}\right)\end{array}$$

where:

• I1 is the Initial value, I1 parameter value.

• I2 is the Pulse value, I2 parameter value.

• TDR is the Rise delay time, TDR parameter value.

• TR is the Rise time, TR parameter value.

• TDF is the Fall delay time, TDF parameter value.

• TF is the Fall time, TF parameter value.

The block uses a small conductance internally to prevent numerical simulation issues. The conductance connects the + and - ports of the device and has a conductance GMIN:

• By default, GMIN matches the GMIN parameter of the Environment Parameters block, whose default value is 1e–12.

• To change GMIN, add an Environment Parameters block to your model and set the GMIN parameter to the desired value.

Ports

Conserving

+ — Positive voltage

electrical

Electrical conserving port associated with the DC current source positive voltage

- — Negative voltage

electrical

Electrical conserving port associated with the DC current source negative voltage

Parameters

Initial value, I1 — Output current initial value

0 A (default)

Value of the output current at time zero, in A.

Pulse value, I2 — Output current asymptotic value

0 A (default)

Asymptotic value of the output current when the output is high, in A.

Rise delay time, TDR — Rise delay time

0 s (default)

Rise time delay, in s.

Rise time, TR — Rise time

1e-9 s (default) | positive scalar

Time it takes the output current to rise from the Initial Value, I1 value to the Pulse Value, I2 value.

Fall delay time, TDF — Fall delay time

0 s (default)

Fall time delay. The default value is 0s, which differs from the SPICE default value.

Fall time, TF — Fall time

1e-9 s (default) | positive scalar

Time it takes the output current to fall from the Pulse value, I2 value to the Initial value, I1 value.

Include parallel conductance, GMIN — Whether to include parallel conductance

Yes (default) | No

Specify if the current source includes a parallel conductance. The value of the parallel conductance, GMIN, depends on whether your model contains an Environment Parameters block.

This table shows the possible values of the parallel conductance, GMIN:

Values of parallel conductance, GMIN

Include parallel conductance, GMIN
Yes		No
Model contains Environment Parameters block	Model does not contain Environment Parameters block	Parallel conductance, GMIN, is not included and it does not affect the current source.
GMIN is equal to the value of the GMIN parameter in the Environment Parameters block.	GMIN = 1e-12 Ohm

Programmatic Use: Add Block

To add the block programmatically, use the add_block function with one of these library block paths as the source.

"ee_lib/Additional Components/SPICE Sources/Exponential Current Source"

Example: add_block("ee_lib/Additional Components/SPICE Sources/Exponential Current Source","myModel/myBlock",MakeNameUnique="on")

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2008a