60.2.1 Power Supply Connections

The following figures shows the recommended power supply connections for switched/linear mode, linear mode only and with battery backup.

Figure 60-1. Power Supply Connection for Switching/Linear Mode
Figure 60-2. Power Supply Connection for Linear Mode Only
Figure 60-3. Power Supply Connection for Battery Backup
Note:
  1. The passive component value shown in figures 58-1, 58-2 & 58-3 is a typical example. Refer to 54.10.1 Voltage Regulator Characteristics for details on specification.
  2. Decoupling capacitors should be placed close to the device for each supply pin pair in the signal group, low ESR capacitors should be used for better decoupling.
  3. An inductor should be added between the external power and the VDD for power filtering.
  4. A ferrite bead has better filtering performance compared to standard inductor at high frequencies. A ferrite bead can be added between the main power supply (VDD) and VDDANA to prevent digital noise from entering the analog power domain. The bead should provide enough impedance (i.e., 50Ω at 20 MHz and 220Ω at 100 MHz) to separate the digital and analog power domains. Make sure to select a ferrite bead designed for filtering applications with a low DC resistance to avoid a large voltage drop across the ferrite bead.