Renesas IS82C55A

Overview

IS82C55A from Intersil is a CMOS Programmable Peripheral Interface IC designed for parallel I/O expansion in 8-bit microprocessor systems such as 80C86/80C88. It provides 24 programmable I/O pins across three 8-bit ports (PA, PB, PC), supports three operational modes (Mode 0/1/2), delivers 2.5mA drive capability per pin, and operates with zero wait states at up to 8MHz clock frequency - enabling direct interface with legacy industrial control panels and embedded instrumentation.

For engineers reviewing the IS82C55A datasheet, IS82C55A pinout, IS82C55A application, or IS82C55A equivalent, key selection considerations include its TTL-compatible 5V operation, bus-hold circuitry eliminating external pull-ups, direct bit set/reset on Port C, enhanced control word read capability, and compatibility with NMOS 8255A-based legacy designs requiring drop-in CMOS power savings.

Technical Context

The IS82C55A implements a dual-group programmable architecture: Group A (Port A + Port C upper 4 bits) and Group B (Port B + Port C lower 4 bits), each independently configurable via software-loaded control words. Its static CMOS design enables low-power operation (10µA standby current) while maintaining full TTL compatibility across military temperature range (–40°C to +85°C).

It supports Mode 0 (basic I/O), Mode 1 (strobed I/O with interrupt-capable handshaking using Port C signals), and Mode 2 (bidirectional bus I/O on Port A with dedicated 5-bit control on Port C). All ports feature latched outputs and buffered inputs; Port A includes both bus-hold high and low circuitry, while Ports B and C provide bus-hold high only.

Key Specifications

Pinout & Package

IS82C55A is packaged in a 44-lead PLCC (Plastic Leaded Chip Carrier) with Pb-free finish, compliant with RoHS and IPC/JEDEC J-STD-020 reflow standards. Pin layout matches industry-standard 8255A footprint for mechanical and thermal compatibility.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar programmable peripheral interface applications.

Compared with Intel 8255A and CP82C55A-5Z, IS82C55A offers superior power efficiency (10µA vs. mA-range standby), extended temperature support, and integrated bus-hold - making it the optimal choice for new industrial designs requiring reliability, low power, and drop-in 8255A compatibility.

Availability

IS82C55A is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, legacy microprocessor system interface, and automated test fixture control requiring stable component supply and long-term lifecycle assurance.

Supply support for IS82C55A 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

Intersil Corporation was a U.S.-based semiconductor company specializing in high-performance analog and mixed-signal ICs, later acquired by Renesas Electronics in 2017. Known for robust industrial-grade timing and interface solutions.

The IS82C55A belongs to Intersil's 82C55A family of CMOS Programmable Peripheral Interfaces, engineered specifically to replace NMOS 8255A in power-constrained, thermally demanding industrial and military applications while preserving full software and hardware compatibility.

FAQ

What is the maximum operating frequency supported by the IS82C55A?

The IS82C55A supports up to 8MHz operation with zero wait states when interfaced to 80C86 or 80C88 microprocessors. This frequency rating is validated under full military temperature range (–40°C to +85°C) and ensures reliable timing margins for read/write cycles, control word loading, and status polling in real-time embedded systems using the IS82C55A.

Does the IS82C55A require external pull-up resistors on its I/O pins?

No, the IS82C55A integrates bus-hold circuitry on all I/O ports (PA, PB, PC), eliminating the need for external pull-up or pull-down resistors in fully CMOS designs. This feature maintains defined logic states on un-driven inputs, reduces BOM count, improves noise immunity, and simplifies PCB layout - a key advantage over NMOS 8255A when implementing the IS82C55A in modern low-power systems.

How does the IS82C55A handle interrupt generation in Mode 1 and Mode 2?

In Mode 1, the IS82C55A generates INTR signals using Port C lines (e.g., INTRA from PC4/PC5 for Port A, INTRB from PC0/PC1 for Port B), controlled by INTE flip-flops set/reset via Port C bit operations. In Mode 2, a single INTR line (INTRA) serves bidirectional Port A, with INTE1 (PC4) enabling OBF-related interrupts and INTE2 (PC4) enabling IBF-related interrupts - all managed through documented control word formats and verified timing in the IS82C55A datasheet.

Can the IS82C55A be used as a direct replacement for the NMOS 8255A in existing designs?

Yes, the IS82C55A is explicitly specified as pin-compatible and functionally equivalent to the NMOS 8255A, with identical pinout, control logic, and register mapping. It requires no PCB changes, firmware modifications, or timing adjustments - delivering immediate power savings (10µA standby vs. ~15mA), extended temperature operation (–40°C to +85°C), and bus-hold functionality while maintaining full interoperability with legacy 8255A-based systems using the IS82C55A.

What package options are available for the IS82C55A, and is RoHS compliance confirmed?

The IS82C55A is supplied in a 44-lead Pb-free PLCC package (RoHS-compliant per Intersil documentation), with matte tin termination and MSL classification meeting or exceeding IPC/JEDEC J-STD-020 requirements for Pb-free reflow. Tape-and-reel packaging is available with "96" suffix. No PDIP or CERDIP variants are assigned to the IS82C55A ordering code - only the 44-lead PLCC variant is valid for this specific part number.