NXP Semiconductors MC68302CRC20C

Overview

MC68302CRC20C from Freescale Semiconductor is an integrated multi-protocol communications processor featuring an MC68000/MC68008 microprocessor core, a dedicated RISC-based communications processor (CP), and system integration block (SIB). It operates at 20 MHz, includes 1152 bytes of on-chip dual-port RAM, three full-duplex Serial Communication Controllers (SCCs), and supports HDLC/SDLC, UART, Bisync, DDCMP, and Totally Transparent protocols - deployed in ISDN terminal adapters and data concentrators.

For engineers reviewing the MC68302CRC20C datasheet, MC68302CRC20C pinout, MC68302CRC20C application, or MC68302CRC20C equivalent, key selection considerations include its 20 MHz clock rating, SCC protocol flexibility, on-chip IDMA controller, dual-port RAM mapping, and TQFP-132 package compatibility with legacy Motorola/Freescale design ecosystems.

Technical Context

The MC68302CRC20C integrates a fully functional MC68000/MC68008 CPU core with a separate RISC main controller for communications processing, enabling concurrent protocol handling without CPU intervention. Its architecture separates peripheral bus traffic via dedicated IDMA and six serial DMA channels tied to three SCCs.

It features two Serial Management Controllers (SMCs) for IDL/GCI channel management, a programmable clock generator, hardware watchdog, DRAM refresh controller, and four chip-select lines with wait-state logic - all coordinated through the System Integration Block for deterministic real-time I/O control.

Key Specifications

Pinout & Package

MC68302CRC20C is housed in a 132-pin Thin Quad Flat Pack (TQFP) with 0.4 mm lead pitch and exposed thermal pad. Pin assignments follow Motorola/Freescale standard layout for MC68302 derivatives, supporting multiplexed address/data bus, dedicated serial I/O, interrupt inputs, and chip-select outputs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC68302FC20C, the MC68302CRC20C offers lower-cost surface-mount assembly and better thermal dissipation in commercial telecom equipment; compared with MC68EN302CFC, it delivers proven serial protocol stability without Ethernet complexity or increased power consumption.

Availability

MC68302CRC20C is available at Aetrix Electronics and suitable for ISDN terminal adapters, data concentrators, and telecom line cards requiring stable component supply, long-lifecycle support, and backward-compatible replacement for legacy Motorola designs.

Supply support for MC68302CRC20C 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) was a leading designer of embedded processors and analog/mixed-signal ICs, founded from Motorola's semiconductor division and focused on automotive, industrial, and networking applications.

The MC68302 product line was developed to deliver single-chip, multi-protocol communications processing for ISDN, data concentration, and serial bridging - targeting cost-sensitive, high-reliability telecom infrastructure where software-defined protocol flexibility mattered more than raw MIPS.

FAQ

What is the maximum operating frequency of the MC68302CRC20C?

The MC68302CRC20C is rated for a maximum clock frequency of 20 MHz, as indicated by the "20" in its part number suffix. This frequency governs the instruction execution rate of the embedded MC68000/MC68008 core and determines timing margins for SCC baud rates, timer resolution, and bus cycle durations. Operation above 20 MHz is not guaranteed and may result in undefined behavior or timing violations.

Does the MC68302CRC20C support Ethernet connectivity natively?

No, the MC68302CRC20C does not include an integrated Ethernet MAC or PHY. Its communications capabilities are limited to serial protocols handled by the three SCCs and two SMCs - including HDLC, UART, Bisync, and V.110. For Ethernet support, designers must use the pin-incompatible MC68EN302 derivative, which adds full IEEE 802.3 compliance and a DRAM controller.

How much on-chip memory does the MC68302CRC20C provide, and what is its architecture?

The MC68302CRC20C integrates 1152 bytes of on-chip dual-port static RAM. This memory is accessible simultaneously by both the MC68000/MC68008 CPU core and the RISC-based communications processor, enabling lock-free buffer sharing for protocol frame handling. It is mapped into the CPU's address space and can be relocated via programmable registers.

Can the MC68302CRC20C operate without external RAM or ROM?

The MC68302CRC20C requires external memory for program storage and runtime data expansion, as its 1152-byte dual-port RAM is insufficient for full application code. While boot code can execute from on-chip RAM using internal vectors, production firmware typically resides in external EPROM or Flash. The device provides four chip-select lines and wait-state logic to interface with diverse memory types.

What serial protocols are supported by the SCCs in the MC68302CRC20C?

The three Serial Communication Controllers (SCCs) in the MC68302CRC20C support HDLC/SDLC, UART, Bisync, DDCMP, Totally Transparent, and V.110 protocols. Each SCC is independently programmable for mode, clock source, and framing - allowing mixed-protocol operation, such as HDLC on SCC1, UART on SCC2, and Bisync on SCC3, all concurrently managed by the RISC communications processor.