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Simulation - Define Digital To Analog Converter

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Use this when editing a Part to define the Part as a Digital To Analog Converter.

Use this on a Digital To Analog Converter component in a schematic design to change its parameters, or to replace it with a DA Converter part using a different number of bits.

These parts are implemented by using Functional Modelling. They have their Spice Type Built-in Function set to DA Converter.

Shortcuts

Default Keys: F7

Default Menu: Simulation

Command: Edit Spice Value/Model

How To Add A Digital To Analog Converter

There are various ways to add a DA Converter to a Schematic Design:

  1. From the Parts toolbar, click on the Digital Generic pop-up to display the Digital Generic toolbar. Click on the D-A Converter button.
  2. From the Parts Browser, click on Spice Category, then on Digital and Generic to display the Digital Generic parts. Drag the D-A Converter part name into the design. Note: This method may not work if you have changed the part categories.
  3. Use Component from the Insert menu to add the Part called D-A Converter from the SPICE library.

Whichever method is used, you should be presented with the Define Digital To Analog Converter Dialog described below. This works because the part named “D-A Converter” has a blank function definition which forces the dialog to be given to get the required definition from you.

How To Define an Digital To Analog Converter

In a Schematic Design, select the DA Converter device(s) that you wish to change. Press F7 or use the Edit Spice Value/Model option from the Simulation menu, or from the shortcut menu.

From a Parts Library edit the required Part. Press the Edit Spice button on the Details tab. Make sure the Built-in Function is set to DA Converter and press the Edit Definition button.

In both cases the following dialog will be displayed:

Number Of Bits

Enter the resolution of converter. Valid values are from 1 to 32.

Output Slew Time

Whenever the input code changes, the output is set on a trajectory to reach the target value in the time specified by this value.

Input

Enter the Offset Voltage and the full scale Range in volts.

See the DAC model in the Simulator’s Device Reference Manual for more details and an example of how the converter works.

Changing the Symbol

If editing a Part, make sure the chosen Number Of Bits match the Symbol that is used by the Part.

If editing a component in a schematic design, pressing OK with changed Number Of Bits will force the component to be replaced with a Part from the Library that matches the new specification. If no suitable Part exists, an error message will be given giving details of the Part that will need to be created.

Editing Multiple Components

If any of the fields are set to then some of the components you are changing have different values for that field. Clear this field and enter the required value for all components, or leave as to tell components to keep their original values for that field.

Analog To Digital Converter | Edit Device Type | Functional Modelling

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