Specification :

Rev. 4235E¨C8051¨C04/04
8-bit Flash
Microcontroller
AT89C51RD2
AT89C51ED2
Features
80C52 Compatible
¨C 8051 Instruction Compatible
¨C Six 8-bit I/O Ports (64 Pins or 68 Pins Versions)
¨C Four 8-bit I/O Ports (44 Pins Version)
¨C Three 16-bit Timer/Counters
¨C 256 Bytes Scratch Pad RAM
¨C 9 Interrupt Sources with 4 Priority Levels
Integrated Power Monitor (POR/PFD) to Supervise Internal Power Supply
ISP (In-System Programming) Using Standard V
CC
Power Supply
2048 Bytes Boot ROM Contains Low Level Flash Programming Routines and a Default
Serial Loader
High-speed Architecture
¨C In Standard Mode:
40 MHz (Vcc 2.7V to 5.5V, both Internal and external code execution)
60 MHz (Vcc 4.5V to 5.5V and Internal Code execution only)
¨C In X2 mode (6 Clocks/machine cycle)
20 MHz (Vcc 2.7V to 5.5V, both Internal and external code execution)
30 MHz (Vcc 4.5V to 5.5V and Internal Code execution only)
64K Bytes On-chip Flash Program/Data Memory
¨C Byte and Page (128 Bytes) Erase and Write
¨C 100k Write Cycles
On-chip 1792 bytes Expanded RAM (XRAM)
¨C Software Selectable Size (0, 256, 512, 768, 1024, 1792 Bytes)
¨C 768 Bytes Selected at Reset for T89C51RD2 Compatibility
On-chip 2048 Bytes EEPROM Block for Data Storage (AT89C51ED2 Only)
¨C 100K Write Cycles
Dual Data Pointer
Variable Length MOVX for Slow RAM/Peripherals
Improved X2 Mode with Independent Selection for CPU and Each Peripheral
Keyboard Interrupt Interface on Port 1
SPI Interface (Master/Slave Mode)
8-bit Clock Prescaler
16-bit Programmable Counter Array
¨C High Speed Output
¨CCompare/Capture
¨C Pulse Width Modulator
¨C Watchdog Timer Capabilities
Asynchronous Port Reset
Full-duplex Enhanced UART with Dedicated Internal Baud Rate Generator
Low EMI (Inhibit ALE)
Hardware Watchdog Timer (One-time Enabled with Reset-Out), Power-off Flag
Power Control Modes: Idle Mode, Power-down Mode
Single Range Power Supply: 2.7V to 5.5V
Industrial Temperature Range (-40 to +85¡ãC)
Packages: PLCC44, VQFP44, PLCC68, VQFP64, PDIL40
Description
AT89C51RD2/ED2 is high performance CMOS Flash version of the 80C51 CMOS sin-
gle chip 8-bit microcontroller. It contains a 64-Kbyte Flash memory block for code and
for data.
The 64-Kbytes Flash memory can be programmed either in parallel mode or in serial
mode with the ISP capability or with software. The programming voltage is internally
generated from the standard V
CC
pin.
1