Check That Every Required Unit of a Multi-Unit Symbol Is Present

A multi-unit symbol spreads one physical component across several schematic graphics. This can make a drawing easier to read, but it also makes a missing power section or unused functional unit easier to overlook. Review the physical package as a whole rather than assuming that the visible signal units account for every required pin.

KiCad’s multi-unit symbol convention describes how devices may be divided into units. The layout of those graphics is a documentation choice. The component still has one package with a specific set of supply, control, and signal requirements.

Start from the package inventory

List each physical component reference that uses more than one symbol unit. For each, record the units defined in the library, the units placed in the schematic, and the physical pins represented by each unit. Compare the combined result with the manufacturer’s pin table.

Do not equate an unused functional unit with a unit that needs no review. An unused amplifier, logic gate, or switch section may have documented input or control requirements. Consult the specific component guidance rather than automatically tying every unused pin to ground or leaving it floating.

Make omissions visible

Check shared references carefully after copying circuitry. Two graphics that look like sections of one device may have been annotated into different packages, while two intended devices may accidentally share one reference. Review the BOM and board update as independent evidence of the physical component count.

Verify the board consequence

1. Run electrical checks with the relevant missing-unit and connection checks enabled.
2. Inspect power and control nets for each affected package.
3. Update the board from the corrected schematic.
4. Compare the footprint count with the intended physical inventory.
5. Trace a representative supply and signal pad for every multi-unit family.

Keep the review record at package level. A list of checked schematic pages is insufficient when one component’s units are distributed across several pages. The record should make it possible to reconstruct how every required physical pin is accounted for.

Finish by adding a clear note for intentional unused sections and correcting the reusable library if the representation contributed to the omission. The hidden power-pin audit addresses the related case where a supply connection exists implicitly but is difficult to see.