Datasheet

137
7701F–AVR–10/12
Atmel ATtiny24/44/84 [Preliminary]
18. Analog-to-Digital Converter
18.1 Features
• 10-bit Resolution
• 1.0 LSB Integral Non-linearity
• ±2 LSB Absolute Accuracy
• 65 - 260µs Conversion Time
• Up to 76kSPS at Maximum Resolution
• Eight Multiplexed Single-Ended Input Channels
• Twelve differential input channels with selectable gain (1x, 20x)
• Temperature sensor input channel
• Optional Left Adjustment for ADC Result Readout
• 0 - V
CC
ADC Input Voltage Range
• 1.1V 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 Canceller
• Unipolar / Bipolar Input Mode
• Input Polarity Reversal channels
18.2 Overview
The Atmel
®
ATtiny24/44/84 features a 10-bit successive approximation analog-to-digital con-
verter (ADC). The ADC is connected to 8-pin port A for external sources. In addition to
external sources, the internal temperature sensor can be measured by the ADC. The analog
multiplexer allows 8 single-ended channels or 12 differential channels from port A. The pro-
grammable gain stage provides amplification steps 0dB (1x) and 26dB (20x) for 12 differential
ADC channels.
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 on page 138.
And internal reference voltage of nominally 1.1V is provided on chip. 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.