Renesas CP82C54-12

Overview

CP82C54-12 from Intersil is a CMOS programmable interval timer IC with three independent 16-bit counters, supporting up to 12MHz clock input frequency, binary or BCD counting, six programmable modes, and TTL-compatible 5V operation - used for real-time clock generation, event counting, and programmable rate control in legacy x86 embedded systems.

For engineers reviewing the CP82C54-12 datasheet, CP82C54-12 pinout, CP82C54-12 application, or CP82C54-12 equivalent, key selection considerations include its 12MHz maximum clock rating, PDIP-24 package compatibility with 80C86/80C88 systems, status read-back command support, and static CMOS low-power operation (10µA standby).

Technical Context

The CP82C54-12 implements three fully independent synchronous down-counters, each configurable via an 8-bit control word specifying mode (0–5), count format (binary/BCD), and read/write sequence. Its internal architecture includes separate count registers (CR), output latches (OL), and counting elements (CE) enabling non-disruptive "on-the-fly" count reads via Counter Latch or Read-Back commands.

It interfaces directly to 8-bit data buses using RD/WR/CS/A0/A1 control logic, supports gate-synchronized counting, and delivers deterministic timing outputs (OUT0–OUT2) with defined setup/hold and delay specifications - e.g., 85ns max data delay from RD at 12MHz, 30ns min CLK high pulse width, and 50ns gate setup time relative to CLK.

Key Specifications

Pinout & Package

CP82C54-12 is supplied in a 24-lead plastic dual in-line package (PDIP), pin-compatible with industry-standard 8254 timers and suitable for through-hole mounting. Thermal resistance θ_JA is 55°C/W (plastic package).

Key Features

Applications

Equivalent & Alternatives

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

Compared with CP82C54-12, CP82C54-12Z offers identical timing performance with RoHS compliance, while CS82C54-12 trades through-hole convenience for surface-mount flexibility - neither is pin-compatible without layout changes, and both retain full functional equivalence for legacy 8254-based firmware.

Availability

CP82C54-12 is available at Aetrix Electronics and suitable for industrial control panels, legacy PC motherboard repairs, and embedded instrumentation requiring stable component supply and long-term obsolescence management.

Supply support for CP82C54-12 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 82C54 family was designed as a CMOS-enhanced, drop-in upgrade to the NMOS 8254 for power-sensitive 8086/80286-era systems - emphasizing low standby current, TTL compatibility, and backward software compatibility.

FAQ

What is the maximum clock frequency supported by the CP82C54-12?

The CP82C54-12 supports a maximum clock input frequency of 12MHz across all three counters, verified in AC electrical specifications (TCLK min = 80ns). This rating applies specifically to the CP82C54-12 variant - lower-speed versions (CP82C54, CP82C54-10) are rated for 8MHz and 10MHz respectively. The 12MHz capability enables sub-microsecond timing resolution in legacy x86 systems.

Does the CP82C54-12 support BCD counting mode?

Yes, the CP82C54-12 supports Binary-Coded Decimal (BCD) counting via the BCD bit (D0) in the control word. When set to '1', the counter operates in 4-decade BCD mode (0000–9999); when '0', it uses 16-bit binary (0–65535). This feature ensures compatibility with legacy systems requiring decimal-aligned timing, such as older industrial controllers and measurement instruments that rely on BCD display drivers.

Can the CP82C54-12 be used as a direct replacement for the NMOS 8254?

Yes, the CP82C54-12 is explicitly designed as a pin-compatible, functionally enhanced replacement for the NMOS 8254. It retains identical pinout, control protocol, and register mapping while adding static CMOS benefits: lower power (10µA standby), higher speed (12MHz vs. 8MHz), and improved noise immunity. Firmware written for the 8254 runs unchanged on the CP82C54-12, making it ideal for drop-in upgrades in existing designs.

What is the purpose of the Read-Back command in the CP82C54-12?

The Read-Back command in the CP82C54-12 allows software to simultaneously latch and read counter status (OUT pin state, null-count flag, and programmed mode) and/or current count values without stopping timing operations. Issued via the control word register with D5/D4 = 0, it enables real-time diagnostics and synchronized monitoring - critical for safety-critical applications like motor control where output state verification must occur mid-operation.

Is the CP82C54-12 available in RoHS-compliant packaging?

Yes, the RoHS-compliant version is designated CP82C54-12Z - a Pb-free variant with 100% matte tin termination, qualified for wave soldering (not reflow). It matches the CP82C54-12 electrically and functionally, including 12MHz operation, 0°C to +70°C temperature range, and PDIP-24 package. Documentation confirms its compliance with IPC/JEDEC J-STD-020 reflow classifications despite being intended for wave-only processing.