| PartNumber | ATMEGA644P-20AU | ATMEGA644P-20AQ | ATMEGA644P-20AQR |
| Description | 8-bit Microcontrollers - MCU AVR 64K FLSH 4K SRAM 2KB EE 20MHZ 5V | 8-bit Microcontrollers - MCU AVR 64K FLSH 4K SRAM 2KB EE 20MHZ 5V | 8-bit Microcontrollers - MCU AVR 64K FLSH 4K SRAM 2KB EE-20MHZ IND,5V |
| Manufacturer | Microchip | Microchip | Microchip |
| Product Category | 8-bit Microcontrollers - MCU | 8-bit Microcontrollers - MCU | 8-bit Microcontrollers - MCU |
| RoHS | Y | Y | Y |
| Mounting Style | SMD/SMT | SMD/SMT | - |
| Package / Case | TQFP-44 | TQFP-44 | TQFP-44 |
| Series | ATmega644P | ATmega644P | ATmega644P |
| Core | AVR | AVR | AVR |
| Data Bus Width | 8 bit | 8 bit | 8 bit |
| Maximum Clock Frequency | 20 MHz | 20 MHz | 20 MHz |
| Program Memory Size | 64 kB | 64 kB | - |
| Data RAM Size | 4 kB | 4 kB | - |
| Number of I/Os | 32 I/O | 32 I/O | - |
| Operating Supply Voltage | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 2.7 V to 5.5 V |
| Minimum Operating Temperature | - 40 C | - 40 C | - |
| Maximum Operating Temperature | + 85 C | + 85 C | - |
| Packaging | Tray | Tray | Reel |
| Height | 1 mm | 1 mm | - |
| Length | 10 mm | 10 mm | - |
| Product | MCU | MCU | MCU |
| Program Memory Type | Flash | Flash | - |
| Width | 10 mm | 10 mm | - |
| Brand | Microchip Technology / Atmel | Microchip Technology / Atmel | Microchip Technology / Atmel |
| Data RAM Type | SRAM | SRAM | - |
| Data ROM Size | 2 kB | 2 kB | - |
| Data ROM Type | EEPROM | EEPROM | - |
| Interface Type | 2-Wire, SPI, UART | 2-Wire, JTAG, SPI, USART | - |
| Moisture Sensitive | Yes | Yes | - |
| Number of Timers/Counters | 3 Timer | 3 Timer | - |
| Processor Series | megaAVR | megaAVR | megaAVR |
| Product Type | 8-bit Microcontrollers - MCU | 8-bit Microcontrollers - MCU | 8-bit Microcontrollers - MCU |
| Factory Pack Quantity | 160 | 160 | 2000 |
| Subcategory | Microcontrollers - MCU | Microcontrollers - MCU | Microcontrollers - MCU |
| Supply Voltage Max | 5.5 V | 5.5 V | - |
| Supply Voltage Min | 2.7 V | 2.7 V, 4.5 V | - |
| Tradename | AVR | AVR | AVR |
| Unit Weight | 0.077179 oz | - | - |