ATtiny261A datasheet(140/292 Pages) ATMEL

140 / 292 page

140

8197A–AVR–10/09

ATtiny261A/461A/861A

15. ADC – Analog to Digital Converter

15.1 Features

• 10-bit Resolution

• 1.0 LSB Integral Non-linearity

• ± 2 LSB Absolute Accuracy

• 13µs Conversion Time

• 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 - VCC 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 / Bipolar Input Mode

• Input Polarity Reversal Mode

15.2 Overview

A 10-bit, successive approximation, Analog to Digital Converter (ADC) is connected to a 11-

channel analog multiplexer, which allows 16 differential voltage input combinations and 11 sin-

gle-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 15-1

on page 141.

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, VCC 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 ADC-

SRB and ADMUX registers.

ATtiny261A Datasheet(PDF) 140 Page - ATMEL Corporation