ATMEGA644P-20AQ Atmel, ATMEGA644P-20AQ Datasheet - Page 251

• Manufacturer Part Number: ATMEGA644P-20AQ
• Description: MCU AVR 64K FLASH 20MHZ 44-TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA644P-20AQ

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Size: 64KB (32K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 2K x 8
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-TQFP, 44-VQFP
• For Use With: ATSTK600 - DEV KIT FOR AVR/AVR32
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

20.7.4
8011O–AVR–07/10
ADC Accuracy Definitions
An n-bit single-ended ADC converts a voltage linearly between GND and V
(LSBs). The lowest code is read as 0, and the highest code is read as 2
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
Figure 20-10. Offset Error
• Gain Error: After adjusting for offset, the Gain Error is found as the deviation of the last
Figure 20-11. Gain Error
• Integral Non-linearity (INL): After adjusting for offset and gain error, the INL is the maximum
0.5 LSB). Ideal value: 0 LSB.
transition (0x3FE to 0x3FF) compared to the ideal transition (at 1.5 LSB below maximum).
Ideal value: 0 LSB
deviation of an actual transition compared to an ideal transition for any code. Ideal value: 0
LSB.
Output Code
Output Code
Offset
Error
ATmega164P/324P/644P
Gain
Error
V
V
REF
REF
Input Voltage
Input Voltage
n
Ideal ADC
Actual ADC
Ideal ADC
Actual ADC
-1.
REF
in 2
n
steps
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