Digital Constant

The Digital Constant models a digital value which is held constant for the entire simulation. The Digital Constant value can be entered in hex, decimal, or binary format and can have between 1 and 32 bits.

In this topic:

Model Name: Digital Constant
Simulator: This device is compatible with the SIMPLIS simulator.
Parts Selector Menu Location: Digital Functions > Functions
Symbol Library: None - the symbol is automatically generated when placed or edited.
Model Library: None - the model is automatically generated when the simulation is run.
Subcircuit Name: SIMPLIS_DIGI1_D_CONSTANT
Symbol:
4-bit digital constant
Multiple Selections: Only one device at a time can be edited.

Editing the Digital Constant

To configure the Digital Constant, follow these steps:

  1. Double click the symbol on the schematic to open the editing dialog to the Parameters tab.
  2. Make the appropriate changes to the fields described in the table below the image.
Label Parameter Description
Value Output value of the digital constant.
Format Determines the input formatting of the VALUE parameter of a digital constant
Number of Bits Number of input bits to the Constant

Usage

The Digital Constant is used whenever a digital signal is held constant for the entire simulation. Although using a DC source or a ground symbol will accomplish the same simulation results, the devices connected to the source or ground reference must have a Ground Ref pin. Using a DC source or a ground reference symbol on a device forces SIMPLIS to convert each input on the device from analog to digital, which can slow down the simulation.

When you use the Digital Constant instead of a DC source or a ground symbol, the inputs are treated as digital signals and the maximum simulation speed is achieved. For more information on maximizing simulation speed, see Maximizing Simulation Speed in Mixed-Mode Simulations

Subcircuit Parameters

Because the Digital Constant model is generated by a template script when the simulation is executed, a hand-coded model cannot be inserted into a netlist. The template script for this device is simplis_make_constant_model.sxscr, which licensed users can download as part of a zip archive of all built-in scripts.

To download the zip archive, follow these steps:

Important: You will be prompted to log in with the user name and password you received with your license file. If you don't have the user name and password, you can email support@simplistechnologies.com with your license information to receive the login credentials. Include a screenshot of the dialog which opens when you run the Help > License Diagnostics... menu.
  1. Click http://www.simetrix.co.uk/simetrix80/scripts.zip to download the script archive.
  2. Enter the user name and password you received with your license file.

The following parameter table defines the parameters used in this model.

Parameter Name Label Data Type Range Units Parameter Description
FORMAT Format String
  • 'DECIMAL'
  • 'BINARY'
  • 'HEX'
 none Determines the input formatting of the VALUE parameter of a digital constant
NUMBITS Number of Bits Integer   none Number of input bits to the Constant
VALUE Value Integer   none Output value of the digital constant.