General description
The P89V51RB2/RC2/RD2 are 80C51 microcontrollers with 16/32/64 kB Flash and 1024 bytes of data RAM.
A key feature of the P89V51RB2/RC2/RD2 is its X2 mode option. The design engineer can choose to run the application with the conventional 80C51 clock rate (12 clocks per machine cycle) or select the X2 mode (6 clocks per machine cycle) to achieve twice the throughput at the same clock frequency. Another way to benefit from this feature is to keep the same performance by reducing the clock frequency by half, thus dramatically reducing the EMI.

Features
■ 80C51 Central Processing Unit
■ 5 V Operating voltage from 0 MHz to 40 MHz
■ 16/32/64 kB of on-chip Flash user code memory with ISP (In-System Programming) and IAP (In-Application Programming)
■ Supports 12-clock (default) or 6-clock mode selection via software or ISP
■ SPI (Serial Peripheral Interface) and enhanced UART
■ PCA (Programmable Counter Array) with PWM and Capture/Compare functions
■ Four 8-bit I/O ports with three high-current Port 1 pins (16 mA each)
■ Three 16-bit timers/counters
■ Programmable watchdog timer
■ Eight interrupt sources with four priority levels
■ Second DPTR register
■ Low EMI mode (ALE inhibit)
■ TTL- and CMOS-compatible logic levels
■ Brown-out detection
■ Low power modes
   ◆ Power-down mode with external interrupt wake-up
   ◆ Idle mode
■ DIP40, PLCC44 and TQFP44 packages