ATMEGA649A-AU Atmel, ATMEGA649A-AU Datasheet - Page 240

• 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

23.2.9
23.3
23.3.1
23.3.2
8284A–AVR–10/10
Mode of Operation
Minimizing power consumption
Static Duty and Bias
1/2 Duty and 1/2 Bias
mum drive time of approximately 2ms when using 1/2 or 1/4 duty, and approximately 2.7ms
when using 1/3 duty. To achieve satisfactory contrast, all segments on the LCD display must
therefore be able to be fully charged/discharged within 2 or 2.7ms, depending on the number of
common pins.
By keeping the percentage of the time the LCD drivers are turned on at a minimum, the power
consumption of the LCD driver can be minimized. This can be achieved by using the lowest
acceptable frame rate, and using low power waveform if possible. The drive time should be kept
at the lowest setting that achieves satisfactory contrast for a particular display, while allowing
some headroom for production variations between individual LCD drivers and displays. Note
that some of the highest LCD voltage settings may result in high power consumption when V
is below 2.0V. The recommended maximum LCD voltage is 2*(V
If all segments on a LCD have one electrode common, then each segment must have a unique
terminal.
This kind of display is driven with the waveform shown in
age across a segment that is on, and SEG1 - COM0 is the voltage across a segment that is off.
Figure 23-3. Driving a LCD with One Common Terminal
For LCD with two common terminals (1/2 duty) a more complex waveform must be used to indi-
vidually control segments. Although 1/3 bias can be selected 1/2 bias is most common for these
displays. Waveform is shown in
segment that is on, and SEG0 - COM1 is the voltage across a segment that is off.
ATmega169A/169PA/329A/329PA/649A/649P/3290A/3290PA/6490A/6490P
V
GND
V
GND
V
GND
-V
LCD
LCD
LCD
LCD
Frame
Frame
SEG0
COM0
SEG0 - COM0
Figure 23-4 on page
V
GND
V
GND
GND
241. SEG0 - COM0 is the voltage across a
LCD
LCD
Figure
Frame
CC
23-3. SEG0 - COM0 is the volt-
Frame
- 0.2V).
SEG1
COM0
SEG1 - COM0
240
CC