NXP Semiconductors MC68331CEH25

Overview

MC68331CEH25 from Freescale Semiconductor is a 32-bit modular microcontroller integrating CPU32 core, System Integration Module (SIM), General-Purpose Timer (GPT), and Queued Serial Module (QSM). It operates at up to 25 MHz system clock, supports external bus interface with 16-bit data/24-bit address bus, and delivers real-time control in industrial automation systems requiring deterministic interrupt handling and low-power stop mode.

For engineers reviewing the MC68331CEH25 datasheet, MC68331CEH25 pinout, MC68331CEH25 application, or MC68331CEH25 equivalent, key selection criteria include its static CPU32 architecture, integrated watchdog and clock monitor, 11-chip-select capability, and dual-function QSM supporting both SCI and QSPI protocols in embedded control designs.

Technical Context

The MC68331CEH25 implements a modular intermodule bus (IMB) architecture linking CPU32, SIM, GPT, and QSM via standardized 24-bit address and 16-bit data pathways. Its SIM provides programmable chip selects (CS0–CS10), periodic interrupt generation, and system protection logic including bus monitor, HALT monitor, and software watchdog timer.

CPU32 executes instructions with full static operation, loop mode, table lookup/interpolate, and hardware breakpoint support. The GPT includes two 16-bit free-running counters, three input capture channels, four output compare channels, and two PWM outputs-enabling precise timing and motor control functions without external peripherals.

Key Specifications

Pinout & Package

MC68331CEH25 is housed in a 132-pin Plastic Quad Flat Package (PQFP) with 0.65 mm lead pitch, JEDEC MS-026 compliant footprint, and thermal pad not present. Pin assignments follow Freescale's documented 132-pin QFP layout with dedicated I/O ports (PE, PF, PC, GP, QS), address/data multiplexing, and module-specific signals (e.g., PQS0–PQS7, PGP0–PGP7).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC68331CEH25, MC68332CAG16 trades clock speed for on-chip memory determinism, while MPC5604B replaces modular legacy architecture with safety-certified Power ISA - making MC68331CEH25 optimal for maintaining existing IMB-based control firmware with extended temperature support.

Availability

MC68331CEH25 is available at Aetrix Electronics and suitable for industrial PLCs, automotive ECU prototyping, factory motion controllers, and energy metering gateways requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MC68331CEH25 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) specialized in high-reliability microcontrollers for automotive, industrial, and aerospace applications before its 2015 acquisition.

The MC68331CEH25 belongs to the 68300 family of modular microcontrollers designed specifically for deterministic real-time control in harsh environments - emphasizing static operation, integrated protection logic, and debug accessibility over raw clock speed.

FAQ

What is the maximum operating frequency of the MC68331CEH25?

The MC68331CEH25 is rated for a maximum system clock frequency of 25 MHz, confirmed by Freescale's official ordering information and electrical specifications. This rating applies across the full –40°C to +125°C operating temperature range. The CPU32 core maintains full static operation at this speed, meaning timing is guaranteed without minimum clock requirements. MC68331CEH25 achieves this via optimized HCMOS process and validated internal pipeline staging.

Does the MC68331CEH25 include on-chip flash or ROM memory?

No, the MC68331CEH25 does not integrate flash or ROM memory. It relies entirely on external memory mapped via its 24-bit address bus and programmable chip-select logic. Boot code must reside in external EPROM or flash connected to CSBOOT, while application code and data reside in external SRAM or DRAM. This architecture allows flexible memory sizing and upgrade paths but requires careful external bus timing design for MC68331CEH25 integration.

How many chip-select outputs does the MC68331CEH25 provide?

The MC68331CEH25 provides eleven dedicated chip-select outputs: CS0 through CS10 plus CSBOOT. Each has individually programmable base address and option registers within the SIM address space (YFFA4C–YFFA76). CSBOOT is hardwired for boot ROM selection, while CS0–CS10 support dynamic bus sizing and wait-state insertion - enabling direct connection to multiple asynchronous peripherals without glue logic in MC68331CEH25-based systems.

Can the MC68331CEH25 generate PWM signals?

Yes, the MC68331CEH25's General-Purpose Timer (GPT) module provides two dedicated PWM outputs: PWMA and PWMB. These are driven by GPT's pulse-width modulator subsystem, which uses the free-running counter and compare registers to set duty cycle and period with 16-bit resolution. PWM generation occurs autonomously without CPU intervention, and PWMA/PWMB pins are assigned to fixed physical locations (pins 129 and 128 in 132-pin PQFP) per MC68331CEH25 pinout documentation.

What debugging interfaces are supported by the MC68331CEH25?

The MC68331CEH25 supports background debugging via dedicated pins: BKPT/DSCLK (breakpoint trigger and debug clock), DSI (debug serial input), and DSO (debug serial output). These signals implement Freescale's proprietary Background Debug Mode (BDM), allowing non-intrusive firmware inspection, register read/write, and breakpoint setting without halting real-time peripheral operation - a key capability confirmed in the CPU32 technical summary and MC68331CEH25 signal function tables.