NXP Semiconductors P87C557E8EFB/01,55

Overview

P87C557E8EFB/01,55 from Philips Semiconductors is an 8-bit microcontroller based on the 80C51 CPU core, featuring 64 kbytes of programmable EPROM, 2048 bytes of internal RAM (256 + 1792), and integrated peripherals including a 10-bit ADC with eight analog inputs, dual 8-bit PWM outputs, I²C-bus serial interface, UART, three 16-bit timers (T0/T1/T2), watchdog timer T3, and PLL-based 32 kHz oscillator with seconds timer. It targets real-time industrial control and instrumentation systems requiring mixed-signal processing and low-power operation.

For engineers reviewing the P87C557E8EFB/01,55 datasheet, P87C557E8EFB/01,55 pinout, P87C557E8EFB/01,55 application, or P87C557E8EFB/01,55 equivalent, key selection considerations include its QFP80 package with dedicated analog/digital supply pins, software-controllable ALE disable for EMI reduction, EPROM-based code security, and dual-oscillator architecture supporting both 3.5–16 MHz standard and 32 kHz PLL clock domains.

Technical Context

The P87C557E8EFB/01,55 implements a derivative 80C51 architecture with extended memory mapping: 64 kbytes internal EPROM (non-expandable), 2048 bytes internal data RAM (256-byte main RAM + 1792-byte AUX-RAM accessed via XRAMP register), and up to 64 kbytes external data memory. Its interrupt system supports 15 sources across two priority levels, with hardware capture/compare registers tied to Timer T2.

It integrates dual clock domains: a primary 3.5–16 MHz XTAL1/XTAL2 oscillator for CPU and peripherals, and a secondary 32 kHz XTAL3/XTAL4 PLL oscillator enabling precise seconds timing and wake-up from Power-down mode. The ADC features programmable autoscan across eight channels, while PWM0/PWM1 provide independent 8-bit resolution outputs with prescaler-controlled frequency.

Key Specifications

Pinout & Package

Package: QFP80 (SOT318-2), plastic quad flat package, 80 leads, body size 14 × 20 × 2.8 mm, lead length 1.95 mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit microcontroller applications.

Compared with P83C557E8EFB/01,55 and P80C557E8EFB/01,55, the P87C557E8EFB/01,55 uniquely balances field-programmability, code security, and full peripheral integration - making it optimal for medium-volume deployments requiring firmware updates, IP protection, and minimal external components.

Availability

P87C557E8EFB/01,55 is available at Aetrix Electronics and suitable for industrial sensor nodes, motor control modules, energy meter interfaces, and automotive body controllers requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for P87C557E8EFB/01,55 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Philips Semiconductors (now NXP Semiconductors) is a global semiconductor leader specializing in high-reliability, mixed-signal ICs for industrial, automotive, and consumer applications.

The P87C557E8EFB/01,55 belongs to the P8xC557E8 family - designed specifically for real-time embedded control tasks demanding integrated analog front-ends, deterministic timing, and robust EMC performance in harsh environments.

FAQ

What is the maximum operating frequency of the P87C557E8EFB/01,55?

The P87C557E8EFB/01,55 supports a maximum system clock frequency of 16 MHz using the XTAL1/XTAL2 oscillator. At this frequency, 58% of instructions execute in 0.75 µs and 40% in 1.5 µs. Multiply/divide operations require 3 µs. The device also supports a separate 32 kHz PLL oscillator for low-power timing functions - this does not affect CPU speed but enables accurate seconds counting and wake-up from Power-down mode.

Does the P87C557E8EFB/01,55 support external program memory expansion?

No, the P87C557E8EFB/01,55 does not support external program memory expansion. Its 64 kbytes of EPROM is internal and non-extendable. When EA is held HIGH at reset, the CPU executes exclusively from internal EPROM; if EA is LOW, it fetches instructions from external program memory - but this configuration is not supported by the P87C557E8EFB/01,55 hardware design and will result in undefined behavior. External data memory up to 64 kbytes remains fully accessible via Ports 0 and 2.

How is code protection implemented in the P87C557E8EFB/01,55?

The P87C557E8EFB/01,55 implements code protection via software-programmable security bits in its EPROM. Once set, these bits prevent read-out of internal program code through any test mode or instruction - including MOVC accesses - even when switching between internal and external memory spaces. Protection is irreversible and enforced at the silicon level. This differs from the P83C557E8EFB/01,55 (mask ROM), which uses a physical security bit, and the P80C557E8EFB/01,55 (ROMless), which has no on-chip code to protect.

Can the ADC and PWM peripherals operate simultaneously on the P87C557E8EFB/01,55?

Yes, the ADC and PWM peripherals operate independently and concurrently on the P87C557E8EFB/01,55. The 10-bit ADC can perform autoscan conversions across all eight channels (P5.0–P5.7) while PWM0 and PWM1 generate continuous output waveforms with separately configurable duty cycles and frequencies. No shared resources or timing conflicts exist between these subsystems, enabling simultaneous analog sensing and actuator control - essential for closed-loop systems like motor drives or adaptive lighting.

What are the power supply requirements for analog and digital sections of the P87C557E8EFB/01,55?

The P87C557E8EFB/01,55 requires two distinct analog supply pairs (VDDA1/VSSA1 for ADC; VDDA2/VSSA2 for PLL oscillator) and four digital supply pairs (VDD1/VSS1, VDD2/VSS2, VDD3/VSS3, VDD4/VSS4). All supplies must be regulated between 4.5 V and 5.5 V. Each VDDn must be decoupled to its adjacent VSSn with ≤100 nF ceramic capacitors placed near the pins. This separation minimizes noise coupling from digital switching into sensitive analog circuits, ensuring ADC accuracy and PLL stability.