Datasheet

9166DS–AVR-01/12

AT32UC3C

6. Supply and Startup Considerations

6.1 Supply Considerations

6.1.1 Power Supplies

The AT32UC3C has several types of power supply pins:

•

VDDIO pins (VDDIO1, VDDIO2, VDDIO3): Power I/O lines. Two voltage ranges are available: 5V or

3.3V nominal. The VDDIO pins should be connected together.

• VDDANA: Powers the Analog part of the device (Analog I/Os, ADC, ACs, DACs). 2 voltage ranges

available: 5V or 3.3V nominal.

• VDDIN_5: Input voltage for the 1.8V and 3.3V regulators. Two Voltage ranges are available: 5V or

3.3V nominal.

• VDDIN_33:

– USB I/O power supply

– if the device is 3.3V powered: Input voltage, voltage is 3.3V nominal.

– if the device is 5V powered: stabilization for the 3.3V voltage regulator, requires external

capacitors

• VDDCORE: Stabilization for the 1.8V voltage regulator, requires external capacitors.

• GNDCORE: Ground pins for the voltage regulators and the core.

• GNDANA: Ground pin for Analog part of the design

• GNDPLL: Ground pin for the PLLs

• GNDIO pins (GNDIO1, GNDIO2, GNDIO3): Ground pins for the I/O lines. The GNDIO pins should be

connected together.

See ”Electrical Characteristics” on page 49 for power consumption on the various supply pins.

For decoupling recommendations for the different power supplies, please refer to the schematic

checklist.

6.1.2 Voltage Regulators

The AT32UC3C embeds two voltage regulators:

• One 1.8V internal regulator that converts from VDDIN_5 to 1.8V. The regulator supplies the

output voltage on VDDCORE.

• One 3.3V internal regulator that converts from VDDIN_5 to 3.3V. The regulator supplies the

USB pads on VDDIN_33. If the USB is not used or if VDDIN_5 is within the 3V range, the

3.3V regulator can be disabled through the VREG33CTL field of the VREGCTRL SCIF

6.1.3 Regulators Connection

The AT32UC3C supports two power supply configurations.

• 5V single supply mode

• 3.3V single supply mode

6.1.3.1 5V Single Supply Mode

In 5V single supply mode, the 1.8V internal regulator is connected to the 5V source (VDDIN_5

pin) and its output feeds VDDCORE.