Overview
The ATmega165A/165PA/325A/325PA/3250A/3250PA/645A/645P/6450A/6450P is a low-power CMOS 8-bit microcontroller based on the AVR enhanced RISC architecture. By executing powerful instructions in a single clock cycle, this microcontroller achieves throughputs approaching 1 MIPS per MHz allowing the system designer to optimize power consumption versus processing speed.

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 (ATmega165PA/645P)
   – Up to 20 MIPS Throughput at 20 MHz
      (ATmega165A/325A/325PA/645A/3250A/3250PA/6450A/6450P)
   – On-Chip 2-cycle Multiplier
• High Endurance Non-volatile Memory segments
   – In-System Self-programmable Flash Program Memory
      • 16K Bytes (ATmega165A/ATmega165PA)
      • 32K Bytes (ATmega325A/ATmega325PA/ATmega3250A/ATmega3250PA)
      • 64K Bytes (ATmega645A/ATmega645P/ATmega6450A/ATmega6450P)
   – EEPROM
      • 512 Bytes (ATmega165A/ATmega165PA)
      • 1K bytes (ATmega325A/ATmega325PA/ATmega3250A/ATmega3250PA)
      • 2K bytes (ATmega645A/ATmega645P/ATmega6450A/ATmega6450P)
   – Internal SRAM
      • 1K Bytes (ATmega165A/ATmega165PA)
      • 2K Bytes (ATmega325A/ATmega325PA/ATmega3250A/ATmega3250PA)
      • 4K Bytes (ATmega645A/ATmega645P/ATmega6450A/ATmega6450P)
   – 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
• QTouch® library support
   – Capacitive touch buttons, sliders and wheels
   – QTouch and QMatrix acquisition
   – Up to 64 sense channels
• 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 with Separate 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
   – 54/69 Programmable I/O Lines
   – 64/100-lead TQFP, 64-pad QFN/MLF and 64-pad DRQFN
• Speed Grade:
   – ATmega 165A/165PA/645A/645P: 0 - 16 MHz @ 1.8 - 5.5V
   – ATmega325A/325PA/3250A/3250PA/6450A/6450P: 0 - 20MHz @ 1.8 - 5.5V
• Temperature range:
   – -40°C to 85°C Industrial
• Ultra-Low Power Consumption (picoPower devices)
   – Active Mode:
      • 1 MHz, 1.8V: 215 µA
      • 32 kHz, 1.8V: 8 µA (including Oscillator)
   – Power-down Mode: 0.1 µA at 1.8V
   – Power-save Mode: 0.6 µA at 1.8V (Including 32 kHz RTC