Data Sheet

Schematic Capture
27
Schematic section completed
Power Connections
Proteus supports a powerful scheme for making power connections implicitly, thus vastly
reducing the number of wires on the schematic. There are three main concepts involved that we
will discuss in turn below.
Hidden Power Pins
Almost all relevant parts in Proteus have their power pins hidden (not visible on the schematic).
The crucial point to remember is that in such cases is that by default the name of the pin
denotes the net to which it will connect.
If you need all pins to be visible on the schematic (e.g. for auditing purposes) consider
using the library import tool (Library Menu -> Import Part) to bring in the parts you need.
This process is quick and easy and works with library parts supplied from all major
vendors.
Power Rail Configuration
The easiest way to manage power nets and connectivity is through the Power Rail
Configuration dialogue form, which is invoked from the Design Menu. If we do this now we can
see that we have three pre-defined power supplies, namely GND, VCC/VDD and VEE.
Changing the combo box at the top we should also see that the GND net is connected to the
GND supply and that both the VCC and the VDD nets are connected to the VCC/VDD supply.
It’s worth examining how this happened more closely:
The GND net is created by connections to an unlabeled ground terminal.
The VDD net is created by connections to the power terminal labeled VDD.
The I2C memory has two hidden power pins, VCC and GND, which are assigned to nets
bearing their names.