Rainbow-electronics ATtiny861_V Instrukcja Użytkownika Pobierz pdf (Strona 142)

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2588B–AVR–11/06

ATtiny261/461/861

19. ADC – Analog to Digital Converter

19.1 Features

• 10-bit Resolution

• 1.0 LSB Integral Non-linearity

• ± 2 LSB Absolute Accuracy

• 65 - 260 µs Conversion Time

• Up to 15 kSPS at Maximum Resolution

• 11 Multiplexed Single Ended Input Channels

• 16 Differential input pairs

• 15 Differential input pairs with selectable gain

• Temperature sensor input channel

• Optional Left Adjustment for ADC Result Readout

• 0 - V

ADC Input Voltage Range

• Selectable 1.1V / 2.56V ADC Voltage Reference

• Free Running or Single Conversion Mode

• ADC Start Conversion by Auto Triggering on Interrupt Sources

• Interrupt on ADC Conversion Complete

• Sleep Mode Noise Cancele

• Unipolar / Bibolar Input Mode

• Input Polarity Reversal Mode

19.2 Overview

The ATtiny261/461/861 features a 10-bit successive approximation ADC. The ADC is connected

to a 11-channel Analog Multiplexer which allows 16 differential voltage input combinations and

11 single-ended voltage inputs constructed from the pins PA7..PA0 or PB7..PB4. The differential

input is equipped with a programmable gain stage, providing amplification steps of 1x, 8x, 20x or

32x on the differential input voltage before the A/D conversion. 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 19-1.

Internal reference voltages of nominally 1.1V or 2.56V are provided On-chip. The Internal refer-

ance voltage of 2.56V, can optionally be externally decoupled at the AREF (PA3) pin by a

capacitor, for better noise performance. Alternatively, V

can be used as reference voltage for

single ended channels. There is also an option to use an external voltage reference and turn-off

the internal voltage reference. These options are selected using the REFS2:0 bits of the ADMUX

control register.

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Rainbow-electronics ATtiny861_V Instrukcja Użytkownika Strona 142