AT91SAM9G20B-CFU(2010) データシートの表示（PDF） - Atmel Corporation

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AT91SAM9G20B-CFU
(Rev.:2010)

AT91 ARM Thumb Microcontrollers

Atmel Corporation 

AT91SAM9G20 Summary

5. Power Considerations

5.1 Power Supplies

The AT91SAM9G20 has several types of power supply pins:

• VDDCORE pins: Power the core, including the processor, the embedded memories and the

peripherals; voltage ranges from 0.9V to 1.1V, 1.0V nominal.

• VDDIOM pins: Power the External Bus Interface I/O lines; voltage ranges between 1.65V and

1.95V (1.8V typical) or between 3.0V and 3.6V (3.3V nominal). The voltage range is

selectable by software.

• VDDIOP pins: Power the Peripherals I/O lines; voltage ranges from 1.65V to 3.6V.

• VDDBU pin: Powers the Slow Clock oscillator, the internal RC oscillator and a part of the

System Controller; voltage ranges from 0.9V to 1.1V, 1.0V nominal.

• VDDPLL pin: Powers the PLL cells; voltage ranges from 0.9V to 1.1V.

• VDDOSC pin: Powers the Main Oscillator cells; voltage ranges from 1.65V to 3.6V

• VDDANA pin: Powers the Analog to Digital Converter; voltage ranges from 3.0V to 3.6V, 3.3V

nominal.

• VDDUSB pin: Powers USB transceiver; voltage ranges from 3.0V to 3.6V.

Ground pins GND are common to VDDCORE, VDDIOM, VDDOSC and VDDIOP pins power

supplies. Separated ground pins are provided for VDDBU, VDDPLL, VDDUSB and VDDANA.

These ground pins are respectively GNDBU, GNDPLL, GNDUSB and GNDANA.

5.2 Programmable I/O Lines

The power supplies pins VDDIOM accept two voltage ranges. This allows the device to reach its

maximum speed either out of 1.8V or 3.3V external memories.

The maximum speed is 133 MHz on the pin SDCK (SDRAM Clock) loaded with 10 pF. The other

signals (control, address and data signals) do not go over 66 MHz, loaded with 30 pF for power

supply at 1.8V and 50 pF for power supply at 3.3V.

The EBI I/Os accept two slew rate modes, Fast and Slow. This allows to adapt the rising and fall-

ing time on SDRAM clock, control and data to the bus load.

The voltage ranges and the slew rates are determined by programming VDDIOMSEL and IOSR

bits in the Chip Configuration registers located in the Matrix User Interface.

At reset, the selected voltage defaults to 3.3V nominal and power supply pins can accept either

1.8V or 3.3V. The user must make sure to program the EBI voltage range before getting the

device out of its Slow Clock Mode.

At reset, the selected slew rates defaults are Fast.

13

6384DS–ATARM–13-Jan-10

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