Certain component symbols do not have a one-to-one correspondence with a package. Rather, several component symbols may correspond to a single physical package. An example is a quad 2-input NAND gate such as the Texas Instruments 74LS00D. For this particular device, up to four component symbols on a schematic diagram may correspond to a single component for the purposes of PCB layout.

To place a multi-section component, select the individual component (in this case, a NAND gate) from the component browser. Immediately prior to placing the component, a section chooser pops up that lists components that have free sections, or allows you to start placing a new component. You must select one of these sections for placement. A Spare Gates Report is available to show sections not used on multi-section components in the design.

As well as being available in components with individual sections as described above, some multi-section TTL and CMOS components are available in a single-package format containing all of the devices. These components' families are found in the component browser, and are appended with “_IC”, as in the component family “74LS_IC”.

In the above figure, (1) shows 74LS00D gates placed as individual sections. These four gates were place from the 74LS component Family, and are combined in one component package when the design is exported to PCB layout. The figure also shows a single-package 74LS00D IC containing four NAND gates (2). This was placed from the 74LS_IC component Family.

Complete the following steps to place a multi-section component with a single package:

  1. Select Place»Component and navigate to the desired Group, Family and Component.
  2. Click to place the IC on the workspace.

      Single-IC components are not available for all multi-section components.

Complete the following steps to place one section of a multi-section component:

  1. Select Place»Component and navigate to the desired Group, Family and Component.
  2. Click OK.

    If this is the first multi-section component of this type (for example, 74LS00D) being placed, a dialog box appears as shown in the figure below:

    If there are already other multi-section components placed, the dialog box will be similar to the following:

    Darker text (1) indicates available sections for placement. Greyed-out text (2) indicates this section has already been placed.

  3. Click on an available section to place it.

      It is a good idea to place all the sections of a multi-section component (U1 in this example) before going to a new multi-section component of the same type. Only instances of the same component type are shown as available to place. In the above example, U1 and “New” are both quad 2-input 74LS00D ICs. If there are other multi-section components in the design, for example 74LS01N, they do not display.

  4. Click on any available section.

    The dialog box closes and a ghost image of the component is attached to your cursor.

  5. Click to place the component in the desired location.
  6. If you selected either Continuous placement for multi-section component only or Continuous placement in the Components tab of the Global Options dialog box, the dialog box re-appears.
  7. Continue placing components from this dialog. When finished, press <Esc> to exit.