ATmega32A datasheet(218/352 Pages) ATMEL

Part #	ATmega32A

Description	8-bit Microcontroller with 32K Bytes In-System Programmable Flash

PDF	352 Pages

Scroll/Zoom	100%

Manufacturer	ATMEL [ATMEL Corporation]

Direct Link	http://www.atmel.com

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218 / 352 page

218

8155B–AVR–07/09

ATmega32A

Figure 22-9. ADC Power Connections

22.7.3

Offset Compensation Schemes

The gain stage has a built-in offset cancellation circuitry that nulls the offset of differential mea-

surements as much as possible. The remaining offset in the analog path can be measured

directly by selecting the same channel for both differential inputs. This offset residue can be then

subtracted in software from the measurement results. Using this kind of software based offset

correction, offset on any channel can be reduced below one LSB.

22.7.4

ADC Accuracy Definitions

An n-bit single-ended ADC converts a voltage linearly between GND and V

REF in 2

n steps

(LSBs). The lowest code is read as 0, and the highest code is read as 2

n-1.

Several parameters describe the deviation from the ideal behavior:

• Offset: The deviation of the first transition (0x000 to 0x001) compared to the ideal transition

(at 0.5 LSB). Ideal value: 0 LSB.

PA4 (ADC4)

PA5 (ADC5)

PA6 (ADC6)

PA7 (ADC7)

AREF

AVCC

GND

PC7

ATmega32A Datasheet(PDF) 218 Page - ATMEL Corporation