ATMEGA164P-B_14 Datasheet, PDF (207/344 Pages) ATMEL Corporation – 8-bit Atmel Microcontroller with 16/32/64Kbytes In-system Programmable Flash

23. ADC - Analog-to-digital Converter
23.1
Features
● 10-bit resolution
● 0.5 LSB integral non-linearity
● ±2 LSB absolute accuracy
● 65 - 260µs conversion time
● Up to 15kSPS at maximum resolution
● 8 multiplexed single ended input channels
● Differential mode with selectable gain at 1x, 10x or 200x
● Optional left adjustment for ADC result readout
● 0 - V_CC ADC input voltage range
● 2.7 - V_CC differential ADC voltage range
● Selectable 2.56V or 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 canceler
23.2
Overview
The Atmel^® ATmega164P-B/324P-B/644P-B features a 10-bit successive approximation ADC. The ADC is connected to an
8-channel analog multiplexer which allows 8 single-ended voltage inputs constructed from the pins of Port A.
The single-ended voltage inputs refer to 0V (GND).
The device also supports 16 differential voltage input combinations. Two of the differential inputs (ADC1, ADC0 and ADC3,
ADC2) are equipped with a programmable gain stage. This provides amplification steps of 0 dB (1x), 20 dB (10x), or 46 dB
(200x) on the differential input voltage before the A/D conversion. Seven differential analog input channels share a common
negative terminal (ADC1), while any other ADC input can be selected as the positive input terminal. If 1x or 10x gain is used,
8-bit resolution can be expected. If 200x gain is used, 6-bit resolution can be expected. Note that internal references of 1.1V
should not be used on 10x and 200x gain.
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 23-1 on page 208.
The ADC has a separate analog supply voltage pin, AVCC. AVCC must not differ more than ±0.3 V from V_CC. See the
Section 23.7 “ADC Noise Canceler” on page 214 on how to connect this pin.
Internal reference voltages of nominally 1.1V, 2.56V or AVCC are provided On-chip. The voltage reference may be
externally decoupled at the AREF pin by a capacitor for better noise performance.
ATmega164P-B/ATmega324P-B/ATmega644P-B [DATASHEET] 207
9255E–AVR–08/14