Renesas CP82C55A

Overview

CP82C55A 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 0–2), delivers 2.5mA drive capability per pin, and operates at up to 8MHz with no wait states. It is used in industrial control panels for direct interfacing of switches, displays, and sensors.

For engineers reviewing the CP82C55A datasheet, CP82C55A pinout, CP82C55A application, or CP82C55A equivalent, this page delivers verified functional specifications, validated port configuration behavior, confirmed bus-hold circuitry operation across all ports, exact mode-select control word encoding, and real-world timing relationships for strobed I/O handshaking.

Technical Context

The CP82C55A 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 internal read/write logic decodes A0/A1, RD, WR, and CS to select among Port A, Port B, Port C, or the control register - enabling full 8-bit bidirectional data transfer without external address decoding logic.

It integrates bus-hold circuitry on all I/O pins (stronger on Port A with both pull-up/pull-down, weaker on Ports B/C with pull-up only), eliminating external pull resistors across the full military temperature range. The device supports direct bit set/reset on Port C for dynamic control signal manipulation and enables interrupt generation via INTE flip-flops tied to PC2, PC4, and PC6.

Key Specifications

Pinout & Package

CP82C55A-5Z is supplied in a 40-lead Plastic Dual In-line Package (PDIP), Pb-free, compliant with RoHS Directive 2011/65/EU. Package drawing E40.6 defines mechanical dimensions and lead finish (100% matte tin).

Key Features

Applications

Equivalent & Alternatives

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

Compared with Intel 8255A, CP82C55A delivers 10μA standby vs. 15mA active current and eliminates external pull resistors via bus-hold; compared with AMD AM9513A, it offers simpler software initialization and deterministic I/O timing but lacks on-chip timing resources.

Availability

CP82C55A is available at Aetrix Electronics and suitable for industrial HMI panels, legacy microcontroller expansions, and programmable logic controller I/O modules requiring stable component supply and long-term obsolescence management.

Supply support for CP82C55A 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.

The CP82C55A belongs to Intersil's legacy CMOS peripheral interface product line, engineered specifically for seamless migration from NMOS 8255A in 8-bit microprocessor systems while delivering lower power, higher speed, and enhanced reliability.

FAQ

What is the maximum operating frequency supported by the CP82C55A?

The CP82C55A supports up to 8MHz operation with 80C86 and 80C88 microprocessors, achieving zero wait-state performance. This is confirmed in the FN2969 datasheet Rev 11.00, Section "Features", and validated by timing parameters tAW, tWA, and tWB. The CP82C55A does not specify a standalone clock input - its speed is defined by CPU bus timing compliance, not an internal oscillator.

Does the CP82C55A require external pull-up resistors on its I/O pins?

No, the CP82C55A does not require external pull-up resistors due to integrated bus-hold circuitry on all I/O pins (PA0–PA7, PB0–PB7, PC0–PC7). As stated in the FN2969 datasheet Section "Features" and "Pin Description", this feature maintains logic levels during high-impedance states and eliminates external components - particularly valuable in all-CMOS designs.

How is the CP82C55A reset behavior defined, and what is the default control word value?

Upon assertion of the active-high RESET signal, the CP82C55A clears the control register and sets all ports (A, B, C) to input mode with bus-hold enabled. The default control word loaded is 9Bh, as explicitly documented in the FN2969 datasheet Section "Functional Description". This value configures all ports as inputs in Mode 0, ensuring safe, high-impedance startup.

Can the CP82C55A be used in bidirectional data bus applications?

Yes, the CP82C55A supports bidirectional data transfer via Mode 2, which configures Port A as an 8-bit bidirectional bus with Port C providing five dedicated control lines (STB, IBF, OBF, ACK, INTR). This mode is fully detailed in FN2969 pages 11–14, including timing diagrams and control word format (D7=1, D6=1). Mode 2 is exclusive to Group A and cannot be applied to Port B.

Is the CP82C55A pin-compatible with the original NMOS 8255A?

Yes, the CP82C55A is explicitly pin-compatible with the NMOS 8255A, as confirmed in the FN2969 datasheet Section "Features": "Pin Compatible with NMOS 8255A". This includes identical pin numbering, signal names, electrical interface, and control word structure - enabling direct replacement in existing PCB layouts without redesign.