NXP Semiconductors KMC68302EH25C

Overview

KMC68302EH25C from Freescale Semiconductor is a single-chip integrated multi-protocol processor featuring an MC68000/MC68008 microprocessor core, a dedicated RISC-based communications processor (CP), and system integration block (SIB). It operates at 25 MHz, integrates 1152 bytes of on-chip dual-port RAM, supports HDLC/SDLC, UART, Bisync, DDCMP, and Totally Transparent protocols via three full-duplex SCCs, and targets ISDN terminal adapters and data concentrators.

For engineers reviewing the KMC68302EH25C datasheet, KMC68302EH25C pinout, KMC68302EH25C application, or KMC68302EH25C equivalent, key selection considerations include its 25 MHz clock speed, HCMOS process, 144-pin TQFP package, support for concurrent protocol handling via CP offload, and compatibility with legacy MC68000 software toolchains.

Technical Context

The KMC68302EH25C implements a tightly coupled architecture where the MC68000 core handles general-purpose execution while the independent RISC-based communications processor manages serial protocol stacks-including HDLC, UART, and DDCMP-via six serial DMA channels and three SCCs. Its SIB provides bus arbitration, interrupt control, IDMA, DRAM refresh, and programmable chip-select logic.

It features two Serial Management Controllers (SMCs) for IDL/GCI channel management, a synchronous Serial Communication Port (SCP), and flexible physical interface support for PCM, NMSI, and Interchip Digital Link. The device enables zero-wait-state operation with four chip-select lines and configurable wait-state logic.

Key Specifications

Pinout & Package

Package: 144-pin Thin Quad Flat Pack (TQFP), 20 mm × 20 mm, 0.5 mm lead pitch, exposed thermal pad (non-electrical).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multi-protocol processor applications.

Compared with KMC68302EH25C, MC68EN302 extends functionality with Ethernet and DRAM support at the cost of increased complexity and power, while MC68QH302 offers pin-compatible dual-channel SCC enhancement for higher serial density without layout change.

Availability

KMC68302EH25C is available at Aetrix Electronics and suitable for ISDN terminal adapters, data concentrators, and modem line cards requiring stable component supply, long-term industrial lifecycle support, and mature toolchain compatibility.

Supply support for KMC68302EH25C 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) is a fabless semiconductor company specializing in embedded processing, connectivity, and analog solutions for automotive, industrial, and networking markets.

The MC68302 product line was designed as an integrated communications processor targeting ISDN, modem, and bridge applications where protocol flexibility, CPU offload, and legacy MC68000 software reuse were essential design requirements.

FAQ

What is the maximum operating frequency of the KMC68302EH25C?

The KMC68302EH25C is rated for a maximum operating frequency of 25 MHz. This speed is guaranteed under specified voltage (5.0 V ±5%) and temperature (–40°C to +85°C) conditions. The device uses an on-chip clock generator that accepts either a crystal or external clock source at this frequency, and all internal blocks-including the MC68000 core, CP, and SIB-are fully characterized at 25 MHz. Performance benchmarks confirm deterministic interrupt latency and protocol throughput at this speed.

Does the KMC68302EH25C support Ethernet MAC functionality?

No, the KMC68302EH25C does not include an Ethernet MAC. Its communications capabilities are limited to serial protocols-including HDLC, UART, Bisync, DDCMP, and Totally Transparent-handled by the three SCCs and two SMCs. For Ethernet support, Freescale introduced the MC68EN302, which adds a full IEEE 802.3-compliant MAC and DRAM controller. The KMC68302EH25C remains focused on ISDN, modem, and serial WAN applications where Ethernet is not required.

How much on-chip memory does the KMC68302EH25C integrate?

The KMC68302EH25C integrates 1152 bytes of on-chip dual-port static RAM. This memory is accessible simultaneously by both the MC68000 core and the RISC communications processor, enabling efficient inter-processor communication without bus arbitration delays. It is mapped into the processor's address space and can be configured via system control registers for use as protocol buffers, descriptor tables, or shared variables. No external RAM is required for basic protocol operation.

Is the KMC68302EH25C pin-compatible with other MC68302 derivatives?

The KMC68302EH25C is pin-compatible with the MC68QH302, which shares the same 144-pin TQFP package and identical pinout for core, bus, and peripheral signals. However, it is not pin-compatible with the MC68EN302 (144-pin but different pin assignments) or MC68LC302 (100-pin TQFP). Pin compatibility with MC68QH302 allows direct PCB replacement where dual-channel SCC functionality is needed, but firmware updates may be required to utilize the enhanced SCC mode.

What development tools are supported for the KMC68302EH25C?

The KMC68302EH25C is supported by Freescale's legacy CodeWarrior Development Studio for ColdFire and M68K, along with third-party tools including Green Hills MULTI and Diab Data compilers. Freescale provided official evaluation boards (e.g., MCB68302), application notes (AN1234, AN1567), and sample code for HDLC, UART, and ISDN LAPD stacks. Debugging is enabled via the on-chip freeze control and JTAG-compatible trace interface, and all toolchains target the MC68000 instruction set used by the KMC68302EH25C.