The power supplies are the first key item to check. Power up the device and perform DC measurement of the supplies as close to the pin as possible. Confirm that each measurement is within the limits defined in the Recommended Operating Conditions section of the data sheet.

Figure 2-1 Two Supply Configuration

Figure 2-2 Three Supply Configuration

The DP83867 supports two configurations for power supplies as shown in Figure 2-1 and Figure 2-2. DP83867 can operate with as few as two supplies. When operating in the three-supply configuration, the VDDA1P8 supply must be stable within 25ms of the VDDA2P5 supply ramping up. There is no sequencing requirement for other supplies when operating in three supply mode. When powering down the DP83867, the VDDA1P8 supply needs to be brought down before the VDDA2P5 supply. Power up the board and verify the sequence of these supplies with an oscilloscope.