Major Chips Description 2-43
2.5 Philips 87C552 System Management Controller
The 87C552 Single-Chip 8-Bit Microcontroller is manufactured in an advanced CMOS process and
is a derivative of the 80C51 microcontroller family. The 87C552 has the same instruction set as the
80C51.
The 87C552 contains a 8kx8 a volatile 256x8 read/write data memory, five 8-bit I/O ports, one 8-bit
input port, two 16-bit timer/event counters (identical to the timers of the 80C51), an additional 16-bit
timer coupled to capture and compare latches, a 15-source, two-priority-level, nested interrupt
structure, an 8-input ADC, a dual DAC pulse width modulated interface, two serial interfaces (UART
and I
2
C-bus), a “watchdog” timer and on-chip oscillator and timing circuits. For systems that require
extra capability, the 87C552 can be expanded using standard TTL compatible memories and logic.
In addition, the 87C552 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 ports, 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.
The device also functions as an arithmetic processor having facilities for both binary and BCD
arithmetic plus bit-handling capabilities. The instruction set consists of over 100 instructions: 49 one-
byte, 45 two-byte, and 17 three-byte. With a 16MHz (24MHz) crystal, 58% of the instructions are
executed in 0.75ms (0.5ms) and 40% in 1.5ms (1ms). Multiply and divide instructions require 3ms
(2ms).
2.5.1 Features
•
80C51 central processing unit
•
8kx8 EPROM expandable externally to 64k bytes
•
An additional 16-bit timer/counter coupled to four capture registers and three compare registers
•
Two standard 16-bit timer/counters
•
256x8 RAM, expandable externally to 64k bytes
•
Capable of producing eight synchronized, timed outputs
•
A 10-bit ADC with eight multiplexed analog inputs
•
Two 8-bit resolution, pulse width modulation outputs
•
Five 8-bit I/O ports plus one 8-bit input port shared with analog inputs
•
I
2
C-bus serial I/O port with byte oriented master and slave functions
•
Full-duplex UART compatible with the standard 80C51
•
On-chip watchdog timer
•
Speed ranges: 16MHz
•
Extended temperature ranges
•
OTP package available
