Rainbow-electronics ATtiny26L Manual do Utilizador descarregar pdf (Página 77)

ATtiny26(L)

1477B–AVR–04/02

Analog to Digital

Converter

Features • 10-bit Resolution

• ±2 LSB Absolute Accuracy

• 0.5 LSB Integral Non-linearity

• Optional Offset Cancellation

• 65 - 260 µs Conversion Time

• 11 Multiplexed Single Ended Input Channels

• 8 Differential Input Channels

• 7 Differential Input Channels with Optional Gain of 20x

• Optional Left Adjustment for ADC Result Readout

• 0 - AVCC ADC Input Voltage Range

• Selectable ADC Reference Voltage

• Free Running or Single Conversion Mode

• Interrupt on ADC Conversion Complete

• Sleep Mode Noise Canceler

The ATtiny26/L features a 10-bit successive approximation ADC. The ADC is connected

to an 11-channel Analog Multiplexer which allows eight differential voltage input combi-

nations or 11 single-ended voltage inputs constructed from seven pins from Port A and

four pins from Port B. Seven of the differential inputs are equipped with a programmable

gain stage, providing amplification steps of 0 dB (1x) and 26 dB (20x) on the differential

input voltage before the A/D conversion. There are four groups of three differential ana-

log input channel selections. All input channels in each group share a common negative

terminal, while another ADC input can be selected as the positive input terminal. The

single-ended voltage inputs refer to 0V (GND).

The ADC contains a Sample and Hold Amplifier 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 46.

The ADC has an analog supply voltage pin, AVCC. The voltage on AVCC must not differ

more than ±0.3V from V

. See the paragraph “ADC Noise Canceling Techniques” on

page 88 on how to connect these pins.

An internal reference voltage of nominally 2.56V is provided On-chip, and this reference

may be externally decoupled at the AREF pin by a capacitor.

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Rainbow-electronics ATtiny26L Manual do Utilizador Página 77