Datasheet

203
7734Q–AVR–02/12
AT90PWM81/161
17. Analog to Digital Converter - ADC
17.1 Features
• 10-bit resolution
• 0.5LSB integral non-linearity
• ±2LSB absolute accuracy
• 8µs - 250µs conversion time
• Up to 120kSPS at maximum resolution
• 11 multiplexed single ended input channels
• One differential input channels with accurate (5%) programmable gain 5, 10, 20, and 40
• Optional left adjustment for ADC result readout
• 0 - V
CC
ADC input voltage range
• Selectable 2.56V 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 canceler
• Temperature sensor
The AT90PWM81/161 features a 10-bit successive approximation ADC. The ADC is connected
to an 15-channel Analog Multiplexer which allows eleven single-ended input. The single-ended
voltage inputs refer to 0V (GND).
The device also supports 2 differential voltage input combinations which are equipped with a
programmable gain stage, providing amplification steps of 14dB (5×), 20dB (10×), 26dB (20×),
or 32dB (40×) on the differential input voltage before the A/D conversion. On the amplified chan-
nels, 8-bit resolution can be expected.
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 204.
The ADC has a separate analog supply voltage pin, AV
CC
. AV
CC
must not differ more than ±0.3V
from V
CC
. See the paragraph “ADC Noise Canceler” on page 210 on how to connect this pin.
Internal reference voltages of nominally 2.56V or AV
CC
are provided On-chip. The voltage refer-
ence may be externally decoupled at the AREF pin by a capacitor for better noise performance.