Datasheet

122
ATtiny25/45/85 [DATASHEET]
2586Q–AVR–08/2013
17. Analog to Digital Converter
17.1 Features
• 10-bit Resolution
• 1 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
17.2 Overview
The ATtiny25/45/85 features a 10-bit successive approximation Analog to Digital Converter (ADC). The ADC is
connected to a 4-channel Analog Multiplexer which allows one differential voltage input and four single-ended volt-
age 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 17-1 on page 123.
Internal reference voltages of nominally 1.1V / 2.56V are provided on-chip. Alternatively, V
CC
can be used as refer-
ence voltage for single ended channels. There is also an option to use an external voltage reference and turn-off
the internal voltage reference.