This document describes the features and characteristics of a product named Rev. 4235G–8051–08/05. The product is 80C52 compatible and features six 8-bit I/O ports (64 pins or 68 pins versions) or four 8-bit I/O ports (44 pins version), three 16-bit timer/counters, 256 bytes scratch pad RAM, 9 interrupt sources with 4 priority levels. Additionally, the product includes an integrated power monitor, supports ISP (In-System Programming), and has a high-speed architecture.
The AT89C51RD2 and AT89C51ED2 are high‑performance 8‑bit CMOS microcontrollers compatible with the 80C52 core. They integrate up to 64 KB of flash program memory, on‑chip RAM, EEPROM (ED2 variant), and a range of peripherals such as timers, UART, SPI, and a programmable counter array.
This document lists the device features, electrical characteristics, package options, special function register (SFR) mappings, and ordering information. It also includes block diagrams, pin tables, and detailed register descriptions for developers and hardware designers.
| Flash Memory Size | 64 KB |
|---|---|
| Expanded RAM (XRAM) | 1792 bytes |
| EEPROM Block (ED2 only) | 2048 bytes |
| Operating Temperature Range | -40 °C to +85 °C |
| Supply Voltage | 2.7 V to 5.5 V |
| Maximum Clock Frequency (Standard Mode) | 40 MHz |
| Write Cycle Endurance | 100 k cycles |
| Interrupt Sources | 9 sources with 4 priority levels |
| Package Options | PLCC44, VQFP44, PLCC68, VQFP64, PDIL40 |
The device provides 64 KB of on‑chip flash program and data memory.
It is offered in PLCC44, VQFP44, PLCC68, VQFP64, and PDIL40 packages.
The device is rated for industrial temperatures from –40 °C to +85 °C.
It includes nine interrupt sources with four priority levels.