NXP Semiconductors MC68EN360CEM25L

Overview

MC68EN360CEM25L from Freescale Semiconductor is a quad integrated communications controller (QUICC) featuring a 32-bit CPU32+ core, dual-port RAM, and an autonomous Communications Processor Module (CPM) with four serial channels (SCC/SMC), supporting HDLC, UART, BISYNC, and transparent protocols. It operates at 25 MHz, integrates system integration logic (SIM60), and targets embedded telecom and industrial control applications requiring deterministic real-time communication offload.

For engineers reviewing the MC68EN360CEM25L datasheet, MC68EN360CEM25L pinout, MC68EN360CEM25L application, or MC68EN360CEM25L equivalent, key selection criteria include CPM-based protocol acceleration, 25 MHz system clock support, dual-bus interface compatibility (32-bit data/32-bit address), and IEEE 1149.1 JTAG test access for in-circuit debugging and production validation.

Technical Context

The MC68EN360CEM25L implements a tightly coupled architecture where the CPU32+ core executes host software while the CPM handles serial I/O, DMA, and protocol processing independently-reducing CPU interrupt load and enabling deterministic latency. Its SIM60 module provides memory management, chip select decoding, interrupt arbitration, and clock generation including CLKOUT signals for peripheral synchronization.

It supports glueless interfacing to DRAM, SRAM, and flash via configurable bus timing, includes 8 KB of on-chip dual-port RAM shared between CPU and CPM, and features a 25 MHz crystal oscillator input (EXTAL/XTAL) with internal PLL for stable system clock derivation-no external clock generator required.

Key Specifications

Pinout & Package

MC68EN360CEM25L is housed in a 256-pin PQFP (Plastic Quad Flat Package) with 0.65 mm pitch, measuring 28 mm × 28 mm. Pin assignments are defined per Freescale's MC68360UM/AD Rev. 4 (1997), Section 2.1 "Signal Descriptions".

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC68EN360CEM25L, MC68360RC25E offers identical functionality with extended thermal tolerance, while MPC860TBCZQ50D4 delivers higher throughput and integrated Ethernet at the cost of architectural discontinuity-making the former a direct reliability upgrade and the latter a generational platform shift.

Availability

MC68EN360CEM25L is available at Aetrix Electronics and suitable for telecom access nodes, industrial protocol gateways, railway signaling controllers, and secure serial terminal servers requiring stable component supply across long-lifecycle embedded programs.

Supply support for MC68EN360CEM25L 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 was a leading designer of embedded processors and analog/mixed-signal ICs, later acquired by NXP Semiconductors in 2015. It specialized in high-reliability, long-lifecycle microcontrollers for industrial, automotive, and networking markets.

The MC68EN360CEM25L belongs to Freescale's QUICC family-designed specifically to offload serial communications processing from host CPUs in mission-critical infrastructure equipment, balancing performance, determinism, and software maintainability.

FAQ

What is the maximum operating frequency supported by the MC68EN360CEM25L?

The MC68EN360CEM25L is factory-specified and tested for stable operation at 25 MHz system clock frequency. This rating is based on its internal CPU32+ core timing, CPM serial channel BRG limits, and SIM60 bus interface specifications. While some systems may achieve marginal overclocking, Freescale's official datasheet and user's manual (MC68360UM/AD Rev. 4) define 25 MHz as the guaranteed maximum-ensuring full compliance with setup/hold times, interrupt latency, and protocol timing margins across voltage and temperature ranges. MC68EN360CEM25L must be operated within this specification for production use.

Does the MC68EN360CEM25L include on-chip memory, and if so, what type and size?

Yes, the MC68EN360CEM25L integrates 8 KB of on-chip dual-port static RAM. This memory is physically shared between the CPU32+ core and the Communications Processor Module (CPM), with independent read/write ports enabling concurrent access without arbitration delay. It is used for CPM microcode storage, protocol descriptor tables, and data buffering-eliminating external SRAM for basic QUICC operation. The memory map is fixed at address 0x00F0_0000–0x00F0_1FFF per the MC68360UM/AD Section 3.1, and no configuration registers control its enablement; it is always active upon reset. MC68EN360CEM25L relies on this RAM for all CPM-initiated transfers.

Can the MC68EN360CEM25L operate without an external crystal oscillator?

No, the MC68EN360CEM25L requires an external crystal connected to the EXTAL and XTAL pins to generate its primary system clock. The device contains an internal oscillator circuit but no PLL bypass or external clock input mode-Section 2.1.10.2 of the MC68360UM/AD explicitly specifies crystal-driven operation only. A 25 MHz fundamental-mode crystal with appropriate load capacitance (typically 12–20 pF) must be used to meet the 25 MHz rating of MC68EN360CEM25L. No alternative clock source (e.g., CMOS oscillator, clock generator IC) is supported in the reference design or characterized in Freescale's electrical specifications.

How many serial communication channels does the MC68EN360CEM25L support, and what protocols are implemented in hardware?

The MC68EN360CEM25L supports four independent serial channels: two Serial Communication Controllers (SCC1 and SCC2) and two Serial Management Controllers (SMC1 and SMC2). SCCs implement HDLC, SDLC, BISYNC, and transparent bit-oriented protocols with hardware CRC-16/32, address recognition, and flag detection. SMCs support UART, HDLC, and transparent byte-oriented modes with automatic RTS/CTS flow control and baud-rate generation. All four channels are managed autonomously by the CPM-no CPU intervention is needed for frame assembly/disassembly. This capability is intrinsic to MC68EN360CEM25L's QUICC architecture and documented in Sections 7.1–7.4 of the MC68360UM/AD.

Is the MC68EN360CEM25L pin-compatible with other members of the MC68360 family, such as the MC68360RC25E?

Yes, the MC68EN360CEM25L is fully pin-compatible with the MC68360RC25E and all other 256-pin PQFP variants in the MC68360 family (e.g., MC68360GC25E, MC68360VC25E). Freescale's ordering information (MC68360/D Product Brief, Section 11) confirms identical package footprint, pin functions, and signal timing across commercial, industrial, and extended temperature grades. This allows direct substitution in existing PCB layouts-only the temperature screening and qualification differ. However, MC68EN360CEM25L is not pin-compatible with PQFP-160 or QFP-208 variants, nor with later PowerQUICC derivatives like MPC860. MC68EN360CEM25L shares full mechanical and electrical interchangeability with MC68360RC25E.