ATmega644PA datasheet(253/468 Pages) ATMEL

Part #	ATmega644PA

Description	8-bit Microcontroller with 16/32/64/128K Bytes In-Sytem Programmable Flash

PDF	468 Pages

Scroll/Zoom	100%

Manufacturer	ATMEL [ATMEL Corporation]

Direct Link	http://www.atmel.com

Logo

253 / 468 page

253

8152G–AVR–11/09

ATmega164PA/324PA/644PA/1284P

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 2n-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.

Figure 22-10. Offset Error

• Gain Error: After adjusting for offset, the Gain Error is found as the deviation of the last

transition (0x3FE to 0x3FF) compared to the ideal transition (at 1.5 LSB below maximum).

Ideal value: 0 LSB

Figure 22-11. Gain Error

• Integral Non-linearity (INL): After adjusting for offset and gain error, the INL is the maximum

deviation of an actual transition compared to an ideal transition for any code. Ideal value: 0

LSB.

Output Code

VREF Input Voltage

Ideal ADC

Actual ADC

Offset

Error

Output Code

VREF Input Voltage

Ideal ADC

Actual ADC

Gain

Error

ATmega644PA Datasheet(PDF) 253 Page - ATMEL Corporation