ATMEGA328-PU comes with Arduino Bootloader. Manufacturer:     Atmel     RoHS:     RoHS Compliant Details     Core:     AVR     Processor Series:     ATMEGA32x     Data Bus Width:     8 bit     Maximum Clock Frequency:     20 MHz     Program Memory Size:     32 KB     Data RAM Size:     2 KB     On-Chip ADC:     Yes     Operating Supply Voltage:     1.8 V to 5.5 V     Operating Temperature Range:     - 40 C to + 85 C     Package / Case:     PDIP-28     Mounting Style:     Through Hole     A/D Bit Size:     10 bit     A/D Channels Available:     6     Data ROM Size:     1 KB     Height:     4.57 mm     Interface Type:     2-Wire, SPI, USART     Length:     34.79 mm     Maximum Operating Temperature:     + 85 C     Minimum Operating Temperature:     - 40 C     Number of Programmable I/Os:     23     Number of Timers:     3     Program Memory Type:     Flash     Factory Pack Quantity:     14     Supply Voltage (Max):     5.5 V     Supply Voltage (Min):     1.8 V     Width:    7.49 mm