ATmega16U4 datasheet(293/408 Pages) ATMEL

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293

7766D–AVR–01/09

ATmega16U4/ATmega32U4

24. Analog to Digital Converter - ADC

24.1

Features

• 10/8-bit Resolution

• 0.5 LSB Integral Non-linearity

• ± 2 LSB Absolute Accuracy

• 65 - 260 µs Conversion Time

• Up to 15 kSPS at Maximum Resolution

• Twelve Multiplexed Single-Ended Input Channels

• One Differential amplifier providing gain of 1x - 10x - 40x - 200x

• Temperature sensor

• Optional Left Adjustment for ADC Result Readout

• 0 - V

CC ADC Input Voltage Range

• Selectable 2.56 V ADC Reference Voltage

• Free Running or Single Conversion Mode

• ADC Start Conversion by Auto Triggering on Interrupt Sources

• Interrupt on ADC Conversion Complete

• Sleep Mode Noise Canceler

The ATmega16U4/ATmega32U4 features a 10-bit successive approximation ADC. The ADC is

connected to an 12-channel Analog Multiplexer which allows six single-ended voltage inputs

constructed from the pins of Port A, and three others from PortB and three others from PortD.

The single-ended voltage inputs refer to 0V (GND).

The device also supports 32 differential voltage input combinations, thanks to a differential

amplifier equipped with a programmable gain stage, providing amplification steps of 0 dB (1x),

10 dB (10x), 16dB (40x) or 23dB (200x) on the differential input voltage before the A/D conver-

sion. Two differential analog input channels share a common negative terminal (ADC0/ADC1),

while any other ADC input can be selected as the positive input terminal. If 1x, 10x or 40x 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 Figure 24-1.

The ADC has a separate analog supply voltage pin, AV

CC. AVCC must not differ more than ±

0.3V from V

CC. See the paragraph “ADC Noise Canceler” on page 301 on how to connect this

pin.

Internal reference voltages of nominally 2.56V 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.

ATmega16U4 Datasheet(PDF) 293 Page - ATMEL Corporation

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