NXP Semiconductors MC68HC000FN16

Overview

MC68HC000FN16 from Freescale Semiconductor (formerly Motorola) is a CMOS 16-bit microprocessor compatible with the M68000 architecture, featuring 24-bit address bus, 16-bit data bus, and 16 MHz maximum clock frequency. It executes 68000 instruction set with supervisor/user privilege modes, supports asynchronous bus timing, and targets embedded control systems requiring deterministic interrupt response and memory-mapped I/O.

For engineers reviewing the MC68HC000FN16 datasheet, MC68HC000FN16 pinout, MC68HC000FN16 application, or MC68HC000FN16 equivalent, key selection considerations include bus cycle compatibility with legacy 68k peripherals, DC/AC electrical specifications at 16 MHz, thermal derating in plastic DIP packages, and exception vector handling for real-time fault recovery.

Technical Context

The MC68HC000FN16 implements the full M68000 programmer's model with eight 32-bit data/address registers, 16-bit external data path, and 24-bit linear address space up to 16 MB. It uses asynchronous bus control with DTACK, BERR, and HALT signals to interface with slow memory and peripherals without wait-state generators.

Its exception processing includes seven autovectored interrupts, bus/address error vectors, and reset vector at $000000, all mapped to fixed locations in low memory. The status register contains interrupt mask bits (I2–I0), supervisor/user mode flag, and condition codes (N/Z/V/C), enabling deterministic context switching.

Key Specifications

Pinout & Package

MC68HC000FN16 is housed in a 64-pin plastic dual in-line package (case 778-02, FN suffix), with 0.3-inch body width and 0.1-inch pin pitch. Pin numbering follows standard DIP convention, starting at pin 1 (top-left corner, notch side).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 16-bit microprocessor applications.

Compared with MC68HC000FN16, the MC68EC000RC16 reduces system cost by eliminating unused pins and features, while the MC68000P16 trades higher power for guaranteed timing margin in noisy industrial environments-neither offers pin-to-pin replacement without layout or decoupling review.

Availability

MC68HC000FN16 is available at Aetrix Electronics and suitable for industrial automation, legacy test equipment, medical diagnostics, and avionics maintenance terminals requiring stable component supply across extended production lifecycles.

Supply support for MC68HC000FN16 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

Freescale Semiconductor (now part of NXP Semiconductors) was a leading designer of embedded processors, known for the 68k family and Power Architecture products before its 2015 acquisition.

The MC68HC000FN16 belongs to the M68000 microprocessor family, designed for general-purpose embedded control applications requiring binary compatibility with existing 68k software and hardware ecosystems.

FAQ

What is the maximum operating frequency of the MC68HC000FN16?

The MC68HC000FN16 is rated for a maximum clock frequency of 16 MHz under commercial temperature conditions (0°C to +70°C). This specification assumes stable +5 V ±5% supply and proper decoupling; exceeding this frequency may result in undefined instruction execution or bus timing violations. The MC68HC000FN16 does not support dynamic frequency scaling or PLL-based clock multiplication.

Does the MC68HC000FN16 support 32-bit instructions and addressing?

The MC68HC000FN16 implements the full M68000 32-bit instruction set architecture, including 32-bit register operations and 32-bit arithmetic, but exposes only a 24-bit address bus (A0–A23) and 16-bit data bus (D0–D15). It cannot access more than 16 MB of physical memory, and 32-bit address calculations are truncated to 24 bits during external bus cycles. The MC68HC000FN16 does not support true 32-bit external data transfers.

How does the MC68HC000FN16 handle bus errors during memory access?

When the MC68HC000FN16 detects an invalid memory access, it asserts the BERR signal and initiates a bus error exception, vectoring to address $000028. The processor pushes the program counter and status register onto the supervisor stack and enters supervisor mode. Recovery requires firmware to inspect the faulting address, correct the condition (e.g., remap memory or disable faulty peripheral), and execute RTE. The MC68HC000FN16 does not auto-retry failed cycles.

What package type is used for the MC68HC000FN16?

The MC68HC000FN16 uses a 64-pin plastic dual in-line package (DIP) with 0.3-inch body width, designated by the FN suffix per Freescale mechanical drawing case 778-02. It is through-hole mountable and compatible with standard 0.1-inch grid PCB footprints. This package lacks thermal pad or exposed die attach, limiting sustained power dissipation to approximately 1.2 W with adequate airflow.

Is the MC68HC000FN16 pin-compatible with the original MC68000P16?

The MC68HC000FN16 shares identical pinout and signal definitions with the bipolar MC68000P16, including AS, DTACK, BERR, HALT, and RESET. However, differences in DC electrical characteristics (e.g., input thresholds, drive strength) and AC timing (e.g., setup/hold margins) require validation of external logic levels and timing margins. The MC68HC000FN16 is not a drop-in replacement without reviewing interface timing and power supply stability.