Overview
The ATmega325/3250/645/6450 provides the following features: 32/64K bytes of In-System Programmable Flash with Read-While-Write capabilities, 1/2K bytes EEPROM, 2/4K byte SRAM, 54/69 general purpose I/O lines, 32 general purpose working registers, a JTAG interface for Boundary-scan, On-chip Debugging support and programming, three flexible Timer/Counters with compare modes, internal and external interrupts, a serial programmable USART, Universal Serial Interface with Start Condition Detector, an 8-channel, 10-bit ADC, a programmable Watchdog Timer with internal Oscillator, an SPI serial port, and five software selectable power saving modes.

Features
• High Performance, Low Power AVR® 8-Bit Microcontroller
• Advanced RISC Architecture
   – 130 Powerful Instructions – Most Single Clock Cycle Execution
   – 32 x 8 General Purpose Working Registers
   – Fully Static Operation
   – Up to 16 MIPS Throughput at 16 MHz
   – On-Chip 2-cycle Multiplier
• High Endurance Non-volatile Memory Segments
   – In-System Self-programmable Flash Program Memory
• 32K Bytes (ATmega325/ATmega3250)
• 64K Bytes (ATmega645/ATmega6450)
   – EEPROM
• 1K bytes (ATmega325/ATmega3250)
• 2K bytes (ATmega645/ATmega6450)
   – Internal SRAM
• 2K bytes (ATmega325/ATmega3250)
• 4K bytes (ATmega645/ATmega6450)
   – Write/Erase Cycles: 10,000 Flash/ 100,000 EEPROM
   – Data retention: 20 years at 85°C/100 years at 25°C(1)
   – Optional Boot Code Section with Independent Lock Bits
• In-System Programming by On-chip Boot Program
• True Read-While-Write Operation
– Programming Lock for Software Security
• JTAG (IEEE std. 1149.1 compliant) Interface
   – Boundary-scan Capabilities According to the JTAG Standard
   – Extensive On-chip Debug Support
   – Programming of Flash, EEPROM, Fuses, and Lock Bits through the JTAG Interface
• Peripheral Features
   – Two 8-bit Timer/Counters with Separate Prescaler and Compare Mode
   – One 16-bit Timer/Counter with Separate Prescaler, Compare Mode, and Capture Mode
   – Real Time Counter withSeparate Oscillator
   –Four PWM Channels
   – 8-channel, 10-bit ADC
   – Programmable Serial USART
   – Master/Slave SPI Serial Interface
   – Universal Serial Interface with Start Condition Detector
   – Programmable Watchdog Timer with Separate On-chip Oscillator
   – On-chip Analog Comparator
   – Interrupt and Wake-up on Pin Change
• Special Microcontroller Features
   – Power-on Reset and Programmable Brown-out Detection
   – Internal Calibrated Oscillator
   – External and Internal Interrupt Sources
   – Five Sleep Modes: Idle, ADC Noise Reduction, Power-save, Power-down, and Standby
• I/O and Packages
   – 53/68 Programmable I/O Lines
   – 64-lead TQFP, 64-pad QFN/MLF, and 100-lead TQFP
• Speed Grade:
   – ATmega325V/ATmega3250V/ATmega645V/ATmega6450V:
• 0 - 4 MHz @ 1.8 - 5.5V, 0 - 8 MHz @ 2.7 - 5.5V
   – ATmega325/3250/645/6450:
• 0 - 8 MHz @ 2.7 - 5.5V, 0 - 16 MHz @ 4.5 - 5.5V
• Temperature range:
   – -40°C to 85°C Industrial
• Ultra-Low Power Consumption
   – Active Mode:
     1 MHz, 1.8V: 350 µA
     32 kHz, 1.8V: 20 µA (including Oscillator)
   – Power-down Mode: 100 nA at 1.8V