NXP Semiconductors MC68020CRC25E

Overview

MC68020CRC25E from Freescale Semiconductor (originally Motorola) is a 32-bit, second-generation enhanced microprocessor with full 32-bit data and address buses (A31–A0, D31–D0), on-chip 256-byte instruction cache, and pipelined architecture operating at 25 MHz. It supports supervisor/user privilege levels, virtual memory management, and coprocessor interface for FPUs or MMUs - deployed in industrial control systems, embedded workstations, and legacy communications equipment requiring deterministic real-time execution.

For engineers reviewing the MC68020CRC25E datasheet, MC68020CRC25E pinout, MC68020CRC25E application, or MC68020CRC25E equivalent, key selection considerations include its 25 MHz maximum clock frequency, 114-pin PGA package, asynchronous bus timing with DSACK handshake, 32-bit linear addressing, and compatibility with M68000-family toolchains and exception model.

Technical Context

The MC68020CRC25E implements a five-stage pipeline (fetch, decode, execute, memory access, write-back) with dynamic bus sizing support for 8-, 16-, and 32-bit transfers. Its on-chip instruction cache is direct-mapped, 256 bytes (64 × 4-byte lines), and uses a write-through policy with no data cache - requiring external memory coherency management.

Bus arbitration is implemented via three dedicated signals (BR, BG, BGACK), supporting up to seven bus masters. Exception handling follows a fixed vector table starting at address 0x00000000, with 256-byte-aligned vectors and full stack frame preservation including program counter, status register, and fault-specific registers like SSW.

Key Specifications

Pinout & Package

MC68020CRC25E is housed in an 114-pin Ceramic Pin Grid Array (CPGA) package with 15 × 15 pin layout (corner pins omitted), 0.100" pin pitch, and integrated heat slug. Thermal resistance θ_JA = 35°C/W per Motorola Electrical Characteristics data.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 32-bit microprocessor applications.

Compared with MC68020CRC25E, MC68030RC25 adds integrated MMU and data cache for OS scalability, while MC68EC020RC25 removes address space and coprocessor capability to reduce cost and power - both require PCB redesign due to pin count and signal set differences.

Availability

MC68020CRC25E is available at Aetrix Electronics and suitable for industrial motion control, legacy telecom infrastructure, and avionics data acquisition requiring stable component supply and long-term obsolescence management.

Supply support for MC68020CRC25E 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, originating from Motorola's semiconductor division and specializing in high-reliability microcontrollers and microprocessors for industrial and automotive markets.

The MC68020CRC25E belongs to the M68000 family second-generation microprocessors, designed specifically for high-performance embedded computing where deterministic real-time behavior, 32-bit flat addressing, and hardware exception handling were essential.

FAQ

What is the maximum operating frequency of the MC68020CRC25E?

The MC68020CRC25E is rated for a maximum clock frequency of 25 MHz, as confirmed in Motorola's M68020 User's Manual Section 10.3 and ordering information tables. This speed defines its instruction throughput ceiling and constrains synchronous peripheral interface timing budgets. The '25' in the suffix explicitly denotes this rating, and operation above 25 MHz violates electrical specifications and may cause pipeline misalignment or bus timing violations.

Does the MC68020CRC25E include an integrated memory management unit (MMU)?

No, the MC68020CRC25E does not integrate an MMU. It supports virtual memory through external MMU chips such as the MC68851, which connect via the coprocessor interface (CPB). Unlike the later MC68030, the MC68020CRC25E relies on discrete components for address translation and page protection - a key architectural distinction verified in Section 1.5 and Section 7 of the official user manual.

What package type and pin count does the MC68020CRC25E use?

The MC68020CRC25E uses an 114-pin Ceramic Pin Grid Array (CPGA) package, documented in Motorola's M68020 User's Manual Section 11.2.1. It features a 15 × 15 grid with corner pins omitted, 0.100" pin pitch, and a ceramic body with integrated thermal slug. This package is distinct from the 132-pin version used by the MC68030 and incompatible with MC68EC020 variants despite shared pinout conventions.

Can the MC68020CRC25E execute unaligned memory accesses?

Yes, the MC68020CRC25E fully supports misaligned 16-bit and 32-bit operand accesses in hardware, unlike earlier M68000 variants. Section 5.2.2 of the user manual confirms automatic splitting of unaligned reads/writes into multiple aligned transfers with correct byte ordering - eliminating software alignment checks and improving C-language compatibility for structures and arrays.

Is the MC68020CRC25E pin-compatible with the MC68EC020RC25?

No, the MC68020CRC25E is not pin-compatible with the MC68EC020RC25. Although both use 114-pin CPGA packages, the MC68EC020 omits 8 address lines (A24–A31), removes coprocessor interface signals (CPB), and reassigns several pins for different functions - as detailed in Section 3.3 and Table 11-2 of the M68020 User's Manual. PCB layout must be redesigned for either device.