Description
AT8xC51Rx2 microcontrollers are high performance ROM versions of the 80C51 8-bit microcontrollers. They contain a 0K, 16K or 32K bytes ROM memory block for program.
The microcontrollers retain all features of the Atmel 80C52 with 256 bytes of internal RAM, a 7-source 4-level interrupt controller and three timer/counters.

Features
• 80C52 Compatible
   – Four 8-bit I/O Ports
   – Three 16-bit Timer/Counters
   – 256 Bytes Scratch Pad RAM
   – 8 Interrupt Sources with 4 Priority Levels
   – Dual Data Pointer
• Variable Length MOVX for Slow RAM/Peripherals
• High-speed Architecture
   – 10 to 40 MHz in Standard Mode
• 16K/32K Bytes On-Chip ROM Program
• T80C51RD2 ROMless Versions
• On-Chip 1024 bytes Expanded RAM (XRAM)
   – Software Selectable Size (0, 256, 512, 768, 1024 bytes)
   – 256 Bytes Selected at Reset for AT87C51RB2/RC2 Compatibility
• Keyboard Interrupt Interface on Port P1
• 8-bit Clock Prescaler
• 64K Program and Data Memory Spaces
• Improved X2 Mode with Independant Selection for CPU and Each Peripheral
• Programmable Counter Array 5 Channels with:
   – High-speed Output
   – Compare/Capture
   – Pulse Width Modulator
   – Watchdog Timer Capabilities
• Asynchronous Port Reset
• Full Duplex Enhanced UART
• Dedicated Baud Rate Generator for UART
• Low EMI (Inhibit ALE)
• Hardware Watchdog Timer (One-time Enabled with Reset-out)
• Power Control Modes
   – Idle Mode
   – Power-down Mode
   – Power-off Flag
• Power Supply: 2.7V to 5.5V or 2.7V to 3.6V
• Temperature Ranges: Commercial (0 to +70°C) and Industrial (-40°C to +85°C)
• Packages: PDIL40, PLCC44, VQFP44