What are the various reference voltage options in PSoC Analog Coprocessor?
PSoC Analog Coprocessor has a Programmable Reference Block (PRB) to generate four different reference voltages using the internal bandgap voltage or the supply voltage VDDA. The reference voltage can be varied in 16 steps between VSS to bandgap voltage or VDDA.
There are two Components provided in PSoC Creator™ IDE to generate and use the reference voltage:
1. Voltage Reference (Vref) Component
2. Programmable Voltage Reference (PVref) Component
- The Vref Component is used to generate a fixed reference voltage with the options of VDDA or the System wide reference as Figure 1 shows.
Figure 1. Vref Component Configuration
If the System wide reference is selected, additional configuration is required in the <Project_Name> .cydwr file to set the reference voltage as Figure 2 shows.
Figure 2. Design-Wide Voltage Reference Settings
Design-Wide Voltage Reference uses one of the four reference voltage circuits from the PRB. It has the following configuration options: Note: Bandgap Reference Gain is a global setting. This setting applies to all the four reference voltage circuits of the PRB
VDDA is the supply voltage. It is set in <Project_Name> .cydwr file so that the Components display the value of VDDA and the derived reference voltages.
Once the above parameters are configured, the Vref Component with System wide reference option can be used. More than one instance of Vref Component is possible in the design; all instances will use the same PRB reference circuit with the same configuration. For more details on the Vref Component, see the Vref Component datasheet.
- Reference Source – 1.2 V Bandgap or VDDA
- Bandgap Reference Gain – 1x or 2x
- Voltage Reference Value – 16 options between VSS to bandgap voltage with gain or VDDA
- VDDA references active during Deep Sleep – Enable or Disable
- PVref Component – Each instance of the PVref Component uses one reference voltage circuit of the PRB. Because there are four reference voltage circuits in the PRB, four instances of the PVref Component can be used in a design. Figure 3 shows the PVref configuration window. You should select the Reference source as Bandgap or VDDA and the Voltage reference from 16 available options.
Figure 3. PVref Component Configuration
Note that the Bandgap voltage source can be 1.2 V or 2.4 V depending on the Bandgap Reference Gain configured in the <Project_Name> .cydwr file as shown in Figure 2.
For more details on the PVRef Component, see the PVref Component datasheet. For information on the architecture of Programmable Reference Block (PRB), see the technical reference manual.