ATMEGA168V_14 Datasheet, PDF (244/377 Pages) ATMEL Corporation – High endurance non-volatile memory segments

ATmega48/88/168
24. Analog-to-digital converter
24.1 Features
• 10-bit resolution
• 0.5LSB integral non-linearity
• ±2LSB absolute accuracy
• 13µs - 260µs conversion time
• Up to 76.9kSPS (Up to 15kSPS at maximum resolution)
• Six multiplexed single ended input channels
• Two additional multiplexed single ended input channels (TQFP and QFN/MLF package only)
• Optional left adjustment for ADC result readout
• 0 - V_CC ADC input voltage range
• Selectable 1.1V ADC reference voltage
• Free running or single conversion mode
• Interrupt on ADC conversion complete
• Sleep mode noise canceler
24.2 Overview
The Atmel ATmega48/88/168 features a 10-bit successive approximation ADC. The ADC is con-
nected to an 8-channel Analog Multiplexer which allows eight single-ended voltage inputs
constructed from the pins of PortC. The single-ended voltage inputs refer to 0V (GND).
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 Figure 24-1
on page 245.
The ADC has a separate analog supply voltage pin, AV_CC. AV_CC must not differ more than ±0.3V
from V_CC. See the paragraph “ADC noise canceler” on page 250 on how to connect this pin.
Internal reference voltages of nominally 1.1V or AV_CC are provided On-chip. The voltage refer-
ence may be externally decoupled at the AREF pin by a capacitor for better noise performance.
The Power Reduction ADC bit, PRADC, in “Minimizing power consumption” on page 41 must be
disabled by writing a logical zero to enable the ADC.
The ADC converts an analog input voltage to a 10-bit digital value through successive approxi-
mation. The minimum value represents GND and the maximum value represents the voltage on
the AREF pin minus 1 LSB. Optionally, AV_CC or an internal 1.1V reference voltage may be con-
nected to the AREF pin by writing to the REFSn bits in the ADMUX Register. The internal
voltage reference may thus be decoupled by an external capacitor at the AREF pin to improve
noise immunity.
2545T–AVR–05/11
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