ATtiny45 datasheet(111/196 Pages) ATMEL

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111

7598H–AVR–07/09

ATtiny25/45/85

18. Analog to Digital Converter

18.1

Features

• 10-bit Resolution

• 0.5 LSB Integral Non-linearity

• ± 2 LSB Absolute Accuracy

• 65 - 260 µs Conversion Time

• Up to 15 kSPS at Maximum Resolution

• Four Multiplexed Single Ended Input Channels

• Two differential input channels with selectable gain

• Temperature sensor input channel

• Optional Left Adjustment for ADC Result Readout

• 0 - V

CC 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 / Bibilar Input Mode

• Input Polarity Reversal Mode

The ATtiny25/45/85 features a 10-bit successive approximation ADC. The ADC is connected to

a 4-channel Analog Multiplexer which allows one differential voltage input and four single-ended

voltage inputs constructed from the pins of Port B. The differential input (PB3, PB4 or PB2, PB5)

is equipped with a programmable gain stage, providing amplification step of 26 dB (20x) 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 18-1.

Internal voltage references of nominally 1.1V or 2.56V are provided On-chip and these voltage

references can optionally be externally decoupled at the AREF (PB0) pin by a capacitor, for bet-

ter noise performance. Alternatively, V

CC can be used as voltage reference 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

ATtiny45 Datenblatt(PDF) 111 Page - ATMEL Corporation