ATmega128A Atmel Corporation, ATmega128A Datasheet - Page 233

• Manufacturer Part Number: ATmega128A
• Manufacturer: Atmel Corporation

Specifications of ATmega128A

• Flash (kbytes): 128 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 53
• Ext Interrupts: 8
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Uart: 2
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 4
• 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: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 4
• Output Compare Channels: 8
• Input Capture Channels: 2
• Pwm Channels: 7
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

23. Analog to Digital Converter
23.1
23.2
8151H–AVR–02/11
Features
Overview
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The ATmega128A features a 10-bit successive approximation ADC. The ADC is connected to
an 8-channel Analog Multiplexer which allows 8 single-ended voltage inputs constructed from
the pins of Port F. The single-ended voltage inputs refer to 0V (GND).
The device also supports 16 differential voltage input combinations. Two of the differential inputs
(ADC1, ADC0 and ADC3, ADC2) are equipped with a programmable gain stage, providing
amplification steps of 0 dB (1x), 20 dB (10x), or 46 dB (200x) on the differential input voltage
before the A/D conversion. Seven differential analog input channels share a common negative
terminal (ADC1), while any other ADC input can be selected as the positive input terminal. If 1x
or 10x gain is used, 8-bit resolution can be expected. If 200x 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
The ADC has a separate analog supply voltage pin, AVCC. AV
±0.3V from V
pin.
Internal reference voltages of nominally 2.56V or AVCC are provided On-chip. The voltage refer-
ence may be externally decoupled at the AREF pin by a capacitor for better noise performance.
10-bit Resolution
0.5 LSB Integral Non-linearity
±2 LSB Absolute Accuracy
13 µs - 260 µs Conversion Time
Up to 76.9 kSPS (Up to 15 kSPS at Maximum Resolution)
8 Multiplexed Single Ended Input Channels
7 Differential Input Channels
2 Differential Input Channels with Optional Gain of 10x and 200x
Optional Left Adjustment for ADC Result Readout
0 - VCC ADC Input Voltage Range
Selectable 2.56V ADC Reference Voltage
Free Running or Single Conversion Mode
Interrupt on ADC Conversion Complete
Sleep Mode Noise Canceler
CC
. See the paragraph
“ADC Noise Canceler” on page 239
CC
must not differ more than
ATmega128A
on how to connect this
Figure
23-1.
233