ATxmega256A3U Atmel Corporation, ATxmega256A3U Datasheet - Page 356

• Manufacturer Part Number: ATxmega256A3U
• Manufacturer: Atmel Corporation

Specifications of ATxmega256A3U

• Flash (kbytes): 256 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 32 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 50
• Ext Interrupts: 50
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 10
• Twi (i2c): 2
• Uart: 7
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 16
• Adc Resolution (bits): 12
• Adc Speed (ksps): 2000
• Analog Comparators: 4
• Resistive Touch Screen: No
• Dac Channels: 2
• Dac Resolution (bits): 12
• Temp. Sensor: Yes
• Crypto Engine: AES/DES
• Sram (kbytes): 16
• Eeprom (bytes): 4096
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: Yes
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.6 to 3.6
• Operating Voltage (vcc): 1.6 to 3.6
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 7
• Output Compare Channels: 22
• Input Capture Channels: 22
• Pwm Channels: 22
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

28.3.4
8331A–AVR–07/11
Internal inputs
Figure 28-4. Single-ended measurement in signed mode
In unsigned mode the negative input is connected to half of the voltage reference (VREF) volt-
age minus a fixed offset. The nominal value for the offset is:
Since the ADC is differential, the input range is VREF to zero for the positive single ended input.
The offset enables the ADC to measure zero crossing in unsigned mode, and allows for calibra-
tion of any positive offset when the internal ground in the device is higher than the external
ground. See
Figure 28-5. Single ended measurement in unsigned mode
Four internal signals can be measured by the ADC.
The internal temperature sensor gives an output voltage that increases linearly with the internal
temperature of the device. One or more calibration points are needed to compute the tempera-
ture from a measurement of the temperature sensor. The temperature sensor is calibrated at
one point in production test, and the result is stored to TEMPESENSE0 and TEMPSENSE1 in
the production signature row. For more calibration condition details refer to device datasheet.
The bandgap voltage is an accurate internal voltage reference.
V
V
enables easy measurement and control of the VCC voltage.
CC
CC
• Temperature sensor
• Bandgap voltage
• V
• DAC output
can be measured directly by scaling it down by a factor of 10 before the ADC input. Thus,
of 1.8V will be measured as 0.18V and V
CC
scaled
Figure 28-11 on page 359
ADC0
ADC1
ADC2
ADC3
ADC4
ADC5
ADC6
ADC7
ADC0
ADC1
ADC2
ADC3
ADC4
ADC5
ADC6
ADC7
ΔV
for details.
VREF
=
2
VREF 0.05
−
CC
Δ
V
of 3.6V will be measured as 0.36V, and this
×
Atmel AVR XMEGA AU
+
-
+
-
356