SAM7X512 Просмотр технического описания (PDF) - Atmel Corporation

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SAM7X512

AT91SAM ARM-based Flash MCU

Atmel Corporation 

SAM7X512/256/128 Summary

5. Power Considerations

5.1 Power Supplies

The SAM7X512/256/128 has six types of power supply pins and integrates a voltage regulator,

allowing the device to be supplied with only one voltage. The six power supply pin types are:

• VDDIN pin. It powers the voltage regulator and the ADC; voltage ranges from 3.0V to 3.6V,

3.3V nominal. In order to decrease current consumption, if the voltage regulator and the ADC

are not used, VDDIN, ADVREF, AD4, AD5, AD6 and AD7 should be connected to GND. In

this case, VDDOUT should be left unconnected.

• VDDOUT pin. It is the output of the 1.8V voltage regulator.

• VDDIO pin. It powers the I/O lines; voltage ranges from 3.0V to 3.6V, 3.3V nominal.

• VDDFLASH pin. It powers the USB transceivers and a part of the Flash and is required for

the Flash to operate correctly; voltage ranges from 3.0V to 3.6V, 3.3V nominal.

• VDDCORE pins. They power the logic of the device; voltage ranges from 1.65V to 1.95V,

1.8V typical. It can be connected to the VDDOUT pin with decoupling capacitor. VDDCORE

is required for the device, including its embedded Flash, to operate correctly.

• VDDPLL pin. It powers the oscillator and the PLL. It can be connected directly to the

VDDOUT pin.

No separate ground pins are provided for the different power supplies. Only GND pins are pro-

vided and should be connected as shortly as possible to the system ground plane.

5.2 Power Consumption

The SAM7X512/256/128 has a static current of less than 60 µA on VDDCORE at 25°C, includ-

ing the RC oscillator, the voltage regulator and the power-on reset when the brownout detector

is deactivated. Activating the brownout detector adds 28 µA static current.

The dynamic power consumption on VDDCORE is less than 90 mA at full speed when running

out of the Flash. Under the same conditions, the power consumption on VDDFLASH does not

exceed 10 mA.

5.3 Voltage Regulator

The SAM7X512/256/128 embeds a voltage regulator that is managed by the System Controller.

In Normal Mode, the voltage regulator consumes less than 100 µA static current and draws 100

mA of output current.

The voltage regulator also has a Low-power Mode. In this mode, it consumes less than 25 µA

static current and draws 1 mA of output current.

Adequate output supply decoupling is mandatory for VDDOUT to reduce ripple and avoid oscil-

lations. The best way to achieve this is to use two capacitors in parallel: one external 470 pF (or

1 nF) NPO capacitor should be connected between VDDOUT and GND as close to the chip as

possible. One external 2.2 µF (or 3.3 µF) X7R capacitor should be connected between VDDOUT

and GND.

Adequate input supply decoupling is mandatory for VDDIN in order to improve startup stability

and reduce source voltage drop. The input decoupling capacitor should be placed close to the

chip. For example, two capacitors can be used in parallel: 100 nF NPO and 4.7 µF X7R.

11

6120GS–ATARM–07-Apr-11

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