| Customer
support |
|
| Digital
circuit symbols missing power/ground pins |
|
| All digital circuit diagram symbols in Circuit
Wizard and Livewire do not have visible power or ground pins
but instead take their power from a hidden digital power supply. |
|
| A separate hidden power supply is available
for both TTL and CMOS digital components. The CMOS supply can
vary between 3 and 15 volts whilst the TTL supply is fixed
at 5 volts. |
| |
| Changing the digital
power supply |
|
| You can control and change the power supply
for digital components via the Power Supply window. |
|
 |
To change the CMOS supply
voltage in Circuit
Wizard, select Power
Supply... from
the Project | Simulation menu. |
|
 |
To change the CMOS supply
voltage in Livewire,
select Power Supply... from the Tools | Simulation menu. |
|
|
| Nets are used to connect the power supply to
the components. The CMOS power supply has the positive terminal
connected to VDD and the negative to VSS. For TTL, the power
supply has the positive terminal connected to VCC and the negative
terminal to GND. |
|
| Adding terminals connected
to any of these named nets allows you to access the hidden
supply. This approach is recommended, particularly
if the circuit is to be made into a PCB layout as all of
the terminals will be connected to the appropriate supply
rail. |
|
| For more information on this topic, click on
the Help button in the Power Supply window. |
| |
