DESCRIPTION
The Philips 80C31/80C51/87C51 is a high-performance microcontroller fabricated with Philips high-density CMOS technology. The CMOS 8XC51 is functionally compatible with the NMOS 8031/8051 microcontrollers. The Philips CMOS technology combines the high speed and density characteristics of HMOS with the low power attributes of CMOS. Philips epitaxial substrate minimizes latch-up sensitivity.
The 8XC51 contains a 4k × 8 ROM (80C51) EPROM (87C51), a 128 × 8 RAM, 32 I/O lines, two 16-bit counter/timers, a five-source, two-priority level nested interrupt structure, a serial I/O port for either multi-processor communications, I/O expansion or full duplex UART, and on-chip oscillator and clock circuits.
In addition, the device has two software selectable modes of power reduction—idle mode and power-down mode. The idle mode freezes the CPU while allowing the RAM, timers, serial port, and interrupt system to continue functioning. The power-down mode saves the RAM contents but freezes the oscillator, causing all other chip functions to be inoperative.

FEATURES
• 8031/8051 compatible
   – 4k × 8 ROM (80C51)
   – 4k × 8 EPROM (87C51)
   – ROMless (80C31)
   – 128 × 8 RAM
   – Two 16-bit counter/timers
   – Full duplex serial channel
   – Boolean processor
• Memory addressing capability
   – 64k ROM and 64k RAM
• Power control modes:
   – Idle mode
   – Power-down mode
• CMOS and TTL compatible
• Five speed ranges at VCC = 5V
   – 12MHz
   – 16MHz
   – 24MHz
   – 33MHz
• Five package styles
• Extended temperature ranges
• OTP package available