Power Supply Connections

The following figures shows the recommended power supply connections for Switched/Linear mode and Linear mode only.

Figure 1. Power Supply Connection for Switching/Linear Mode
Figure 2. Power Supply Connection for Linear Mode Only
Table 1. Power Supply Connections
Signal Name Recommended Pin Connection Description
VDDIO 1.62V to 3.63V

Decoupling/filtering capacitors 100 nF(1,2) and 10 µF(1)

Decoupling/filtering inductor 10 μH(1,3)

Digital supply voltage
VDDANA 1.62V to 3.63V

Decoupling/filtering capacitors 100 nF(1,2) and 10 µF(1)

Ferrite bead(4) prevents the VDD noise interfering with VDDANA

Analog supply voltage
VDDCORE 0.9V to 1.2V typical

Decoupling/filtering capacitors 100 nF(1,2) and 1µF(1)

Linear regulator mode: Core supply voltage output/external decoupling pin

Switched regulator mode: Core supply voltage input, must be connected to VDDOUT via inductor

VDDOUT Switching regulator mode: 10 µH inductor (5)

Linear regulator mode: Not connected

On-chip Switching mode regulator output
GND   Ground
GNDANA   Ground for the analog power domain
  1. 1.These values are only given as a typical example.
  2. 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. 3.An inductor should be added between the external power and the VDD for power filtering.
  4. 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 and VDDANA to prevent digital noise from entering the analog power domain. The bead should provide enough impedance (for example, 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.
  5. 5.Refer to the Buck Converter section in the Electrical Characteristics chapter.