ATxmega16D4 Atmel Corporation, ATxmega16D4 Datasheet - Page 227

• Manufacturer Part Number: ATxmega16D4
• Manufacturer: Atmel Corporation

Specifications of ATxmega16D4

• Flash (kbytes): 16 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 32 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 34
• Ext Interrupts: 34
• Usb Speed: No
• Usb Interface: No
• Spi: 4
• Twi (i2c): 2
• Uart: 2
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 12
• Adc Resolution (bits): 12
• Adc Speed (ksps): 200
• Analog Comparators: 2
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 2
• Eeprom (bytes): 1024
• 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: 4
• Output Compare Channels: 14
• Input Capture Channels: 14
• Pwm Channels: 14
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

20.3.4
8210B–AVR–04/10
Internal inputs
The negative input is connected to internal ground in signed mode.
Figure 20-4. 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, unsigned mode is achieved by dividing the reference by two inter-
nally, resulting in an input range from VREF to zero for the positive single ended input. The
offset enables the ADC to measure zero cross detection in unsigned mode, and to calibrate any
positive offset where the internal ground in the device is higher than the external ground. See
Figure 20-11 on page 230
Figure 20-5. Single ended measurement in unsigned mode
Three internal analog signals can be selected as input and measured by the ADC.
The voltage output from an internal temperature reference can be measured with the ADC and
the voltage output will give an ADC result representing the current temperature in the microcon-
troller. During production test, the ADC measures a fixed temperature using the internal
temperature sensor, and the value is store in the production calibration row and can be used for
temperature sensor calibration.
The bandgap voltage is an accurate voltage reference inside the microcontroller that is the
source for other internal voltage references.
• Temperature sensor
• Bandgap voltage
• V
CC
scaled
ADC14
ADC15
ADC14
ADC15
ADC...
ADC0
ADC1
ADC2
ADC3
ADC0
ADC1
ADC2
ADC3
...
...
...
for details.
ΔV
VREF
=
2
VREF 0.05
−
Δ
V
×
+
-
+
-
ADC
ADC
XMEGA D
227