Microchip Technology MCP2221 - 3.3.6 Configure DAC Tab

Testing Board Features
 2016 Microchip Technology Inc. DS50002480A-page 31
3.3.6 Configure DAC Tab
The MCP4726 DAC (Digital-to-Analog Converter) uses an MCP1525 as a 2.5V voltage
reference, thus allowing it to generate a fixed voltage no matter if the board’s power
(V
DD
) is set to 3.3V or 5V.
The MCP4726 also has the option to set a 2x reference gain, which means that only if
the MCP2221 I
2
C Demonstration Board works at 5V (jumper J19 is set to 5V), then the
analog voltage output can be as high as 5V. This option can be enabled from the PC
application.
3.3.6.1 TAB OPERATION
Follow these steps to set the voltage value for the DAC:
1. Select the Configure DAC tab.
2. From the Select Reference Voltage radio button group, choose the preferred
voltage. The default value is 2.5V. Note that users should only select 5V if the
V
DD
value is 5V.
3. To set the output voltage, use one of the following formats:
- Inside the text box corresponding to the “Write Value in Volts” text box, type
in the numeric value;
or
- Select the “Set Voltage in Real Time” check box, then adjust the slider. The
resulting values will be shown in the text box corresponding to “Write Value
in Volts (Example: 2.35)” label. Use a period (.) and not a comma (,) to write
the value.
4. Regardless of the method used to set the output voltage, the voltages are only
submitted to the board after the user clicks the Set Voltage button. The value is
also displayed below the “Current Voltage” label, inside the corresponding
read-only text box.
5. To read the output voltage value back from the chip’s register, click the Read
Voltage Data button. The value is displayed in the read-only text box, below the
“Current Voltage” label.