Optimum Design Associates Blog

As we’ve covered in other posts on schematic symbols, one of the key goals of a librarian is to maintain consistency, both in terms of visual appearance of a symbol, and parity with a manufacturer’s data sheet. Establishing a set of standards which all schematic symbols must abide by allows for more timely part identification, and cleaner, easier to read schematics. With that in mind, let’s take a look at display settings for schematic symbols within Optimum’s library.

Base Symbol: adg1407-dil28.1 (dual inline IC, 28 pin)

Optimum’s symbol library makes extensive use of various abbreviations in symbol names. Our previous posts have dealt with the pins of schematic symbols, and the general theory behind some of our naming conventions. A look into our naming abbreviations could have been joined with our overarching naming convention post, but we feel the large number of different abbreviations warrant a standalone post.

Part Type Qualifier Abbreviations

While having appropriate labeling and naming for schematic symbols is the most critical aspect of organizing your symbol library, ensuring that pins for all symbols are consistent is equally critical. This maintains visual consistency on the schematic, and consistent connection points within DxDesigner. All of the pin settings must be considered: visual aspects such as length and orientation, as well as technical considerations such as inverted pins and location of connection points. Optimum maintains rigorous standards for pins on schematic symbols, let's take a more in depth look. 

Much like your library of footprints or cells, proper naming conventions are critical for easy identification and utilization of schematic symbols. This can be complicated by the fact that generic symbols can be utilized for certain component types, whereas more intricate components, such as connectors or ICs, will require unique symbols with different naming conventions. In this series of DxDesigner tutorials we’ll take a look at the organizational methods of Optimum librarians, beginning with symbol naming, and moving on to pin considerations, and overall symbol library structure.

Symbol Name Prefixes

At various points in your design process it may be necessary to modify the pin naming or numbering of components in your design. Be it an error in the part’s original creation, pin or gate swapping for placement and layout concerns, any number of reasons. Modifying symbol pin names or cell pin numbers after the elements are associated with a part will invalidate the part. Fortunately, Library Manager has built in utilities to assist with modifying pin labeling in these instances.

Dimensioning data can be an invaluable tool to PCB designers and librarians. It helps ensure accuracy and consistency, with necessary information regarding part size readily visible. For a designer this can ensure that a component will be useable in a high density layout. From a librarian's perspective, dimensioning data allows for quick reference to a component data sheet for the purposes of checking. 

General Process Overview

                Select a symbol

                Export pins to ms excel spreadsheet

                Make pin changes in the spreadsheet

                Import pins and generate symbol automatically

While it won't always be necessary, there will come times when Cells must be deleted from your part library. Perhaps an error was discovered when trying to place a part on a PCB design, or a new generic part for a passive component will be utilized, say an 0402 capacitor. Chances are those Cells will be referenced by multiple parts in your PDB database. Because they reference parts in the database, deleting these cells isn't as simple as clicking the delete button and calling it a day. The steps below outline how to properly delete a cell from your component library if its referenced by parts within the library. 

Mentor’s Display Control gives designers and librarians myriad options for influencing how a design is displayed on the screen. The goal of any display scheme is to have any information a designer needs readily visible, so more time is spent working, as opposed to scouring the design for the portion you wish to work on. While the individual colors chosen are personal preference, best practices exist for both library and PCB design work. Let’s take a look at how many of Optimum’s librarians configure their Display Controls.