Datasheet

17
6500AS–ATARM–11-Dec-09
SAM3S Summary
5. Power Considerations
5.1 Power Supplies
The SAM3S product has several types of power supply pins:
• VDDCORE pins: Power the core, the embedded memories and the peripherals; voltage
ranges from 1.62V and 1.95V.
• VDDIO pins: Power the Peripherals I/O lines (Input/Output Buffers); USB transceiver; Backup
part, 32kHz crystal oscillator and oscillator pads; ranges from 1.62V and 3.6V
• VDDIN pin: Voltage Regulator Input, ADC, DAC and Analog Comparator Power Supply;
Voltage ranges from 1.8V to 3.6V
• VDDPLL pin: Powers the PLLA, PLLB, the Fast RC and the 3 to 20 MHz oscillator; voltage
ranges from 1.62V and 1.95V.
5.2 Voltage Regulator
The SAM3S embeds a voltage regulator that is managed by the Supply Controller.
This internal regulator is intended to supply the internal core of SAM3S. It features two different
operating modes:
• In Normal mode, the voltage regulator consumes less than 700 µA static current and draws
80 mA of output current. Internal adaptive biasing adjusts the regulator quiescent current
depending on the required load current. In Wait Mode quiescent current is only 7 µA.
• In Backup mode, the voltage regulator consumes less than 1 µA while its output (VDDOUT) is
driven internally to GND. The default output voltage is 1.80V and the start-up time to reach Nor-
mal mode is inferior to 100 µs.
For adequate input and output power supply decoupling/bypassing, refer to the Voltage Regula-
tor section in the Electrical Characteristics section of the datasheet.
5.3 Typical Powering Schematics
The SAM3S supports a 1.62V-3.6V single supply mode. The internal regulator input connected
to the source and its output feeds VDDCORE. Figure 5-1 shows the power schematics.
As VDDIN powers the voltage regulator, the ADC/DAC and the analog comparator, when the
user does not want to use the embedded voltage regulator, it can be disabled by software via
the SUPC (note that it is different from Backup mode).