ATmega1280 Atmel Corporation, ATmega1280 Datasheet - Page 275

• Manufacturer Part Number: ATmega1280
• Manufacturer: Atmel Corporation

Specifications of ATmega1280

• Flash (kbytes): 128 Kbytes
• Pin Count: 100
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 86
• Ext Interrupts: 32
• Usb Speed: No
• Usb Interface: No
• Spi: 5
• Twi (i2c): 1
• Uart: 4
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 16
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 8
• Eeprom (bytes): 4096
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8 to 5.5
• Operating Voltage (vcc): 1.8 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 6
• Output Compare Channels: 16
• Input Capture Channels: 4
• Pwm Channels: 15
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

26. ADC – Analog to Digital Converter
26.1
2549N–AVR–05/11
Features
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
The ATmega640/1280/1281/2560/2561 features a 10-bit successive approximation ADC. The
ADC is connected to an 8/16-channel Analog Multiplexer which allows eight/sixteen single-
ended voltage inputs constructed from the pins of Port F and Port K. The single-ended voltage
inputs refer to 0V (GND).
The device also supports 16/32 differential voltage input combinations. Four of the differential
inputs (ADC1 & ADC0, ADC3 & ADC2, ADC9 & ADC8 and ADC11 & ADC10) are equipped with
a programmable gain stage, providing amplification steps of 0 dB (1×), 20 dB (10×) or 46 dB
(200×) on the differential input voltage before the ADC conversion. The 16 channels are split in
two sections of 8 channels where in each section seven differential analog input channels share
a common negative terminal (ADC1/ADC9), while any other ADC input in that section can be
selected as the positive input terminal. If 1× or 10× gain is used, 8 bit resolution can be
expected. If 200× gain is used, 7 bit resolution can be expected.
The ADC contains a Sample and Hold circuit which ensures that the input voltage to the ADC is
held at a constant level during conversion. A block diagram of the ADC is shown in
on page
The ADC has a separate analog supply voltage pin, AVCC. AVCC must not differ more than
±0.3V from V
pin.
Internal reference voltages of nominally 1.1V, 2.56V or AVCC are provided On-chip. The voltage
reference may be externally decoupled at the AREF pin by a capacitor for better noise
performance.
The Power Reduction ADC bit, PRADC, in
must be disabled by writing a logical zero to enable the ADC.
10-bit Resolution
1 LSB Integral Non-linearity
±2 LSB Absolute Accuracy
13µs - 260µs Conversion Time
Up to 76.9kSPS (Up to 15kSPS at Maximum Resolution)
16 Multiplexed Single Ended Input Channels
14 Differential input channels
4 Differential Input Channels with Optional Gain of 10× and 200×
Optional Left Adjustment for ADC Result Readout
0V - V
2.7V - V
Selectable 2.56V or 1.1V ADC Reference Voltage
Free Running or Single Conversion Mode
Interrupt on ADC Conversion Complete
Sleep Mode Noise Canceler
CC
276.
CC
ADC Input Voltage Range
Differential ADC Voltage Range
CC
. See the paragraph
ATmega640/1280/1281/2560/2561
“ADC Noise Canceler” on page 283
“PRR0 – Power Reduction Register 0” on page 56
on how to connect this
Figure 26-1
275