ATMEGA649A-AU Atmel, ATMEGA649A-AU Datasheet - Page 226

• Manufacturer Part Number: ATMEGA649A-AU
• Description: IC MCU AVR 64K FLASH 64TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA649A-AU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: SPI, UART/USART, USI
• Peripherals: Brown-out Detect/Reset, LCD, POR, PWM, WDT
• Number Of I /o: 54
• 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): 1.8 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-TQFP
• Processor Series: ATmega
• Core: AVR
• Data Bus Width: 8 bit
• Data Ram Size: 4 KB
• Interface Type: SPI, USART
• Maximum Clock Frequency: 16 MHz
• Number Of Programmable I/os: 54
• Number Of Timers: 3
• Operating Supply Voltage: 3.3 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Operating Temperature Range: - 40 C to + 85 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

22.7
22.7.1
8284A–AVR–10/10
ADC Noise Canceler
Analog Input Circuitry
The ADC features a noise canceler that enables conversion during sleep mode to reduce noise
induced from the CPU core and other I/O peripherals. The noise canceler can be used with ADC
Noise Reduction and Idle mode. To make use of this feature, the following procedure should be
used:
1. Make sure that the ADC is enabled and is not busy converting. Single Conversion mode
2. Enter ADC Noise Reduction mode (or Idle mode). The ADC will start a conversion once
3. If no other interrupts occur before the ADC conversion completes, the ADC interrupt will
Note that the ADC will not be automatically turned off when entering other sleep modes than Idle
mode and ADC Noise Reduction mode. The user is advised to write zero to ADEN before enter-
ing such sleep modes to avoid excessive power consumption.
The analog input circuitry for single ended channels is illustrated in
analog source applied to ADCn is subjected to the pin capacitance and input leakage of that pin,
regardless of whether that channel is selected as input for the ADC. When the channel is
selected, the source must drive the S/H capacitor through the series resistance (combined resis-
tance in the input path).
The ADC is optimized for analog signals with an output impedance of approximately 10 kΩ or
less. If such a source is used, the sampling time will be negligible. If a source with higher imped-
ance is used, the sampling time will depend on how long time the source needs to charge the
S/H capacitor, with can vary widely. The user is recommended to only use low impedant sources
with slowly varying signals, since this minimizes the required charge transfer to the S/H
capacitor.
Signal components higher than the Nyquist frequency (f
kind of channels, to avoid distortion from unpredictable signal convolution. The user is advised
to remove high frequency components with a low-pass filter before applying the signals as
inputs to the ADC.
ATmega169A/169PA/329A/329PA/649A/649P/3290A/3290PA/6490A/6490P
must be selected and the ADC conversion complete interrupt must be enabled.
the CPU has been halted.
wake up the CPU and execute the ADC Conversion Complete interrupt routine. If another
interrupt wakes up the CPU before the ADC conversion is complete, that interrupt will be
executed, and an ADC Conversion Complete interrupt request will be generated when
the ADC conversion completes. The CPU will remain in active mode until a new sleep
command is executed.
ADC
/2) should not be present for either
Figure 22-8 on page 227
226
An