ATMEGA649V-8AI Atmel, ATMEGA649V-8AI Datasheet - Page 231

• Manufacturer Part Number: ATMEGA649V-8AI
• Description: IC AVR MCU FLASH 64K 1.8V 64TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA649V-8AI

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: SPI, UART/USART, USI
• Peripherals: Brown-out Detect/Reset, LCD, POR, PWM, WDT
• Number Of I /o: 53
• 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, 64-VQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

23.1.10
23.2
23.2.1
23.2.2
2552K–AVR–04/11
Mode of Operation
Minimizing power consumption
Static Duty and Bias
1/2 Duty and 1/2 Bias
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
is on, and SEG0 - COM1 is the voltage across a segment that is off.
V
GND
V
GND
V
GND
-V
LCD
LCD
LCD
LCD
Frame
Frame
SEG0
COM0
SEG0 - COM0
Figure
23-4. SEG0 - COM0 is the voltage across a segment that
ATmega329/3290/649/6490
V
GND
V
GND
GND
LCD
LCD
Figure
Frame
CC
23-3. SEG0 - COM0 is the volt-
Frame
- 0.2V).
SEG1
COM0
SEG1 - COM0
231
CC