AT90PWM3B-16SUR Atmel, AT90PWM3B-16SUR Datasheet - Page 242

• Manufacturer Part Number: AT90PWM3B-16SUR
• Description: MCU AVR 8K FLASH 16MHA 32SOIC
• Manufacturer: Atmel
• Series: AVR® 90PWM Lightingr

Specifications of AT90PWM3B-16SUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 27
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 11x10b; D/A 1x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 105°C
• Package / Case: 32-SOIC (7.5mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

21.6.3
21.6.4
242
AT90PWM2/3/2B/3B
Offset Compensation Schemes
ADC Accuracy Definitions
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 shortening both differential inputs using the AMPxIS bit with both inputs unconnected.
(See “Amplifier 0 Control and Status register – AMP0CSR” on page 255.
1Control and Status register – AMP1CSR” on page
tracted in software from the measurement results. Using this kind of software based offset
correction, offset on any channel can be reduced below one LSB.
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:
•
Figure 21-10. Offset Error
•
Offset: The deviation of the first transition (0x000 to 0x001) compared to the ideal transition
(at 0.5 LSB). Ideal value: 0 LSB.
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
Output Code
Offset
Error
256.). This offset residue can be then sub-
V
REF
Input Voltage
n
-1.
and
Ideal ADC
Actual ADC
REF
See “Amplifier
4317J–AVR–08/10
in 2
n
steps