NXP Semiconductors MC68EC000EI12

Overview

MC68EC000EI12 from Motorola is a 16-/32-bit embedded controller CPU implementing the M68000 instruction set architecture, featuring a 24-bit address bus (16 MB address space), 16-bit data bus, no on-chip MMU or FPU, and operation at up to 12 MHz. It targets cost-sensitive industrial control, instrumentation, and legacy embedded systems requiring ROM-based boot and minimal peripheral integration.

For engineers reviewing the MC68EC000EI12 datasheet, MC68EC000EI12 pinout, MC68EC000EI12 application, or MC68EC000EI12 equivalent, key selection criteria include its lack of memory management unit, external bus timing compatibility with MC68000, 5 V single-supply operation, and suitability for deterministic real-time firmware execution without cache or pipelining complexity.

Technical Context

The MC68EC000EI12 executes the full M68000 integer instruction set-including data movement, arithmetic, logical, bit manipulation, and program control instructions-with identical addressing modes (register direct, absolute short/long, PC-relative, indexed, etc.) and condition code behavior as the MC68000. It supports supervisor/user privilege levels via status register bits but omits the MC68010's virtual memory extensions and all MMU-related instructions.

Its bus interface uses asynchronous, non-multiplexed address/data signaling with discrete /AS, /DS, /UDS, /LDS, and /R/W control lines; it requires external latching for address capture and generates no internal clock-relying on an externally supplied 24 MHz crystal or TTL-compatible clock signal to derive its 12 MHz core frequency.

Key Specifications

Pinout & Package

MC68EC000EI12 is housed in a 64-pin ceramic quad flat pack (CQFP) package with 0.65 mm lead pitch, compliant with MIL-STD-883 Class B screening for extended temperature operation (–40°C to +85°C). Pin functions are electrically and logically identical to the MC68000 but omit pins associated with MMU and coprocessor support.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC68EC000EI12, MC68000RC12 offers identical functionality at lower cost but reduced environmental robustness, while MC68EC020RC16 delivers substantial performance and memory scalability at the expense of compatibility and design continuity.

Availability

MC68EC000EI12 is available at Aetrix Electronics and suitable for industrial control, test equipment, and avionics maintenance interfaces requiring stable component supply across long-lifecycle production programs.

Supply support for MC68EC000EI12 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

Motorola Semiconductor (now NXP Semiconductors) pioneered the M68000 family in the early 1980s, establishing a foundational 16-/32-bit architecture widely adopted in workstations, embedded systems, and consumer electronics.

The MC68EC000 product line was engineered specifically for cost-optimized, high-reliability embedded applications-removing MMU/FPU to reduce die size and power while retaining full M68000 software compatibility and deterministic real-time behavior.

FAQ

What is the maximum operating frequency of the MC68EC000EI12?

The MC68EC000EI12 is rated for a maximum clock input frequency of 24 MHz, which internally divides to produce a 12 MHz core execution rate. This frequency defines its instruction throughput ceiling and establishes timing constraints for external memory and peripheral access cycles, requiring /DTACK assertion within specified setup/hold windows for reliable operation.

Does the MC68EC000EI12 include an on-chip memory management unit (MMU)?

No, the MC68EC000EI12 does not contain an on-chip MMU. It implements only the base M68000 instruction set and lacks all MMU-related registers, instructions (e.g., PFLUSH, PTEST), and bus signals required for virtual memory translation. Memory management must be implemented externally using discrete logic or companion chips such as the MC68851.

Is the MC68EC000EI12 pin-compatible with the standard MC68000?

Yes, the MC68EC000EI12 is functionally and pin-compatible with the MC68000 in all essential bus interface and control signal assignments. It omits only the MC68010+ MMU-specific pins (e.g., /CAS0–/CAS2, /MREQ), making it a drop-in replacement in designs that do not utilize virtual memory features.

What voltage supply does the MC68EC000EI12 require?

The MC68EC000EI12 operates exclusively from a single 5 V ± 5% supply. It does not support split-rail (e.g., +5 V and +12 V) or low-voltage (e.g., 3.3 V) operation. All I/O pins are 5 V TTL-compatible, and the device draws approximately 120 mA typical at 12 MHz, necessitating appropriate decoupling and thermal management in the PCB layout.

How does the MC68EC000EI12 handle reset and boot sequence?

Upon assertion of the active-low RESET signal, the MC68EC000EI12 initializes all internal registers, disables interrupts, and begins instruction fetch from absolute address $000000. This vector location must contain a long-word address pointing to the initial program counter value, enabling direct boot from ROM or Flash without external initialization firmware.