ATMEGA48V_06 Datasheet, PDF (244/374 Pages) ATMEL Corporation – 8-bit Microcontroller with 8K Bytes In-System Programmable Flash

22. Analog-to-Digital Converter
22.1 Features
• 10-bit Resolution
• 0.5 LSB Integral Non-linearity
• ± 2 LSB Absolute Accuracy
• 13 - 260 µs Conversion Time
• Up to 76.9 kSPS (Up to 15 kSPS at Maximum Resolution)
• 6 Multiplexed Single Ended Input Channels
• 2 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
22.2 Overview
The ATmega48/88/168 features a 10-bit successive approximation ADC. The ADC is connected
to an 8-channel Analog Multiplexer which allows eight single-ended voltage inputs constructed
from the pins of Port A. 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 22-1
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.
244 ATmega48/88/168
2545J–AVR–12/06