Renesas CP82C88

Overview

CP82C88 from Intersil is a CMOS bus controller designed to generate timing and control signals for 80C86, 80C88, 8086, 8088, 8089, 80186, and 80188 microprocessor-based systems. It provides MRDC, MWTC, IORC, IOWC, AMWC, AIOWC, INTA, DEN, DT/R, ALE, and MCE/PDEN outputs with three-state command drivers, 5V single-supply operation, and static CMOS low-power design (ICCSB ≤ 10 µA). It supports both System Bus and I/O Bus modes via the IOB pin.

For engineers reviewing the CP82C88 datasheet, CP82C88 pinout, CP82C88 application, or CP82C88 equivalent, key selection considerations include its dual-bus mode configuration (IOB), compatibility with legacy Intel CPUs, timing response delays (e.g., TCLML ≤ 35 ns at 12 MHz), and direct replacement capability for bipolar 8288 in 5V TTL-compatible systems.

Technical Context

The CP82C88 decodes S0/S1/S2 status inputs from compatible microprocessors to generate synchronized command outputs-MRDC, MWTC, IORC, IOWC, AMWC, AIOWC, and INTA-with precise timing relative to CLK and AEN. Its control logic implements two distinct operational modes: System Bus mode (IOB = LOW) requires AEN arbitration before command issuance, while I/O Bus mode (IOB = HIGH) enables immediate I/O command activation independent of AEN.

It features dual-function MCE/PDEN output that serves as Master Cascade Enable in System Bus mode and Peripheral Data Enable in I/O Bus mode. All command outputs are three-state, with VOH ≥ 3.0 V at IOH = –12 mA and VOL ≤ 0.5 V at IOL = +12 mA, ensuring robust drive into standard TTL/CMOS loads without external buffers.

Key Specifications

Pinout & Package

CP82C88Z is supplied in a 20-lead plastic dual in-line package (PDIP) with Pb-free finish per RoHS, compliant with JEDEC MS-001 and Intersil drawing E20.3.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bus controller applications.

Compared with the bipolar 8288, CP82C88 delivers 1000× lower standby current and integrated advanced write commands, while CS82C88 offers identical functionality in a space-saving PLCC package-neither is pin-compatible with CP82C88Z's PDIP form factor, requiring layout revision for physical substitution.

Availability

CP82C88 is available at Aetrix Electronics and suitable for industrial PLC backplanes, legacy x86 embedded controllers, and military avionics data acquisition systems requiring stable component supply and long-term obsolescence management.

Supply support for CP82C88 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 is a U.S.-based semiconductor company specializing in precision analog and power management ICs, acquired by Renesas Electronics in 2017.

The 82C88 product line was developed to provide CMOS-compatible bus control for Intel 8086-family microprocessors, enabling lower-power, higher-reliability replacements for bipolar 8288 in commercial and industrial computing systems.

FAQ

What is the primary function of the CP82C88 in an 8086-based system?

The CP82C88 serves as the central bus controller, decoding S0/S1/S2 status signals from the 8086 or 8088 CPU to generate precisely timed command outputs-including MRDC, MWTC, IORC, IOWC, AMWC, AIOWC, INTA, DEN, and DT/R-that coordinate memory and I/O transactions. CP82C88 eliminates the need for external bus drivers due to its +12 mA output drive capability and supports both System Bus and I/O Bus modes via the IOB pin, making it essential for deterministic timing in legacy x86 architectures.

Does CP82C88 support 12 MHz operation, and what are the critical timing limits?

Yes, CP82C88 is fully specified for 12 MHz operation per FN2979 Rev 3.00. At this frequency, the maximum command active delay (TCLML) is 35 ns, the maximum AEN-to-command enable time (TAELCV) is 250 ns, and the minimum CLK high time (TCHCL) is 34 ns. These parameters ensure reliable synchronization with 80186/80188 processors running at 12 MHz, and CP82C88 maintains full DC/AC specification compliance across 0°C to +70°C without derating.

How does the IOB pin affect CP82C88 behavior, and what are the practical implications?

The IOB pin selects between two mutually exclusive operational modes: when IOB = HIGH, CP82C88 enters I/O Bus mode, enabling immediate I/O command activation (IORC/IOWC) independent of AEN-ideal for dedicated peripheral buses. When IOB = LOW, it enters System Bus mode, gating all commands (including memory) behind AEN for arbitration in multi-master systems. This dual-mode capability makes CP82C88 uniquely suited for hybrid architectures, and CP82C88's pinout and logic ensure no external glue logic is needed to switch modes.

Can CP82C88 directly replace a bipolar 8288, and what design changes are required?

Yes, CP82C88 is a pin- and function-compatible drop-in replacement for the bipolar 8288, requiring no PCB changes. CP82C88 matches all input thresholds (VIH = 2.0 V, VIL = 0.8 V), output drive levels, and timing waveforms. Key advantages include 1000× lower standby current (10 µA vs. ~10 mA), integrated AMWC/AIOWC advanced write commands, and improved noise immunity. No schematic or layout modifications are needed-only verification of decoupling (0.1 µF between VCC and GND) and thermal margin.

What is the role of the MCE/PDEN pin, and how does it differ between bus modes?

The MCE/PDEN pin is dual-function: in System Bus mode (IOB = LOW), it acts as Master Cascade Enable (MCE), an active-HIGH signal used during interrupt acknowledge cycles to read cascade addresses from an 82C59A PIC; in I/O Bus mode (IOB = HIGH), it becomes Peripheral Data Enable (PDEN), an active-LOW signal that enables I/O bus transceivers independently of DEN. This dynamic reassignment is handled entirely within CP82C88's internal logic-no external mode-select circuitry is required, and CP82C88 ensures correct timing alignment in both configurations per Table 1 and Figures 1–3.