NXP Semiconductors MC68LC302CPU20CT

Overview

MC68LC302CPU20CT from Freescale is a low-cost integrated multiprotocol processor based on a static 68000 core, operating at 20 MHz with 5 V supply, featuring two full-duplex SCCs, three timers (including watchdog and PIT), 1152-byte dual-port RAM, and four chip-select lines - used in embedded communications controllers and portable protocol gateways.

For engineers reviewing the MC68LC302CPU20CT datasheet, MC68LC302CPU20CT pinout, MC68LC302CPU20CT application, or MC68LC302CPU20CT equivalent, key selection considerations include its 100-pin TQFP package, absence of SCC3, glueless memory interface via WEH/WEL/OE, PLL support for 32 kHz or 4 MHz crystals, and dual wake-up pin capability in low-power standby modes.

Technical Context

The MC68LC302CPU20CT implements a static M68000 CPU core with 8/16-bit data bus support and integrated system integration block (SIB) containing interrupt controller, PIO ports, and dual-port RAM. Its communication peripheral block (CP) integrates two independent SCCs supporting HDLC/SDLC, UART, BISYNC, and transparent modes with autobaud.

It replaces the MC68302's third SCC and external bus arbitration pins (BR/BG/BGACK) with dedicated memory control signals (WEH/WEL/OE) and adds PLL-related pins (XFC, VCCSYN, GNDSYN, MODCLK). The device supports slave mode (DISCPU), freeze debugging (PGA only), and periodic wake-up via PIT or two GPIO pins.

Key Specifications

Pinout & Package

MC68LC302CPU20CT is housed in a 100-pin TQFP (Thin Quad Flat Pack) package with 0.5 mm pitch, lead-free (RoHS-compliant) construction, and thermal pad exposed on underside for enhanced heat dissipation in continuous operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar integrated multiprotocol processor applications.

Compared with MC68302RC20 and MC68332ACPV16, the MC68LC302CPU20CT offers optimized cost and footprint for dual-SCC protocol applications with strict space and power constraints - sacrificing SCC3 and bus arbitration for TQFP compactness and lower system BOM cost.

Availability

MC68LC302CPU20CT is available at Aetrix Electronics and suitable for industrial protocol gateways, PCMCIA modem cards, handheld data terminals, and intelligent serial peripherals requiring stable component supply across extended product lifecycles.

Supply support for MC68LC302CPU20CT 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 and analog/mixed-signal ICs, focused on automotive, industrial, and networking applications.

The MC68LC302 product line delivers cost-optimized, low-power versions of the MC68302 IMP family - targeting portable, space-constrained, and battery-operated communications equipment requiring dual-protocol serial processing.

FAQ

What is the core architecture of the MC68LC302CPU20CT?

The MC68LC302CPU20CT features a static 68000 CPU core, fully compatible with the M68000 instruction set and supporting both 8-bit and 16-bit data bus configurations. Unlike dynamic cores, it requires no external refresh and enables true zero-power sleep states. This architecture ensures software compatibility with existing 68000-based firmware while delivering lower power consumption than the original MC68302. The MC68LC302CPU20CT maintains full register and exception model fidelity with the classic 68000 family.

Does the MC68LC302CPU20CT support external bus mastership?

No, the MC68LC302CPU20CT does not support full external bus mastership as implemented in the MC68302. Pins BR, BG, and BGACK are omitted to reduce pin count. However, an external master can still gain bus control using the HALT pin in a simplified handshake. Full bus arbitration remains available only in DISCPU (slave) mode, where BR/BG/BGACK are remapped from IPL pins. This limitation makes the MC68LC302CPU20CT unsuitable for systems requiring concurrent multi-master bus operation.

What clock sources does the MC68LC302CPU20CT support?

The MC68LC302CPU20CT supports two primary clock sources: a 4 MHz crystal directly driving the on-chip PLL, or a 32 kHz crystal for ultra-low-power operation - the PLL then synthesizes the 20 MHz system clock. External clock input is also supported via EXTAL. The XFC, VCCSYN, and GNDSYN pins provide dedicated PLL power and feedback paths. This dual-frequency capability allows designers to minimize system power in battery-powered applications while maintaining full 20 MHz performance when needed. The MC68LC302CPU20CT does not require external clock dividers or buffers.

How many serial communication controllers does the MC68LC302CPU20CT include?

The MC68LC302CPU20CT includes two independent full-duplex serial communication controllers (SCC1 and SCC2), each supporting HDLC/SDLC, UART, BISYNC, and transparent modes with autobaud detection. SCC3 - present in the MC68302 - is removed to reduce pin count and cost. Each SCC has dedicated TXD/RXD/RCLK/CTS/RTS/CD pins, with some shared via port A (PA0–PA10). This dual-SCC configuration is sufficient for most bridge, gateway, and modem applications where three channels are unnecessary. The MC68LC302CPU20CT thus balances feature set and integration for targeted use cases.

What package type and temperature range does the MC68LC302CPU20CT use?

The MC68LC302CPU20CT is supplied in a 100-pin Thin Quad Flat Pack (TQFP) package with 0.5 mm lead pitch and RoHS-compliant finish. It is rated for commercial temperature range (0 °C to +70 °C). This package enables compact PCB layouts and fits mechanically constrained environments such as PCMCIA cards. The TQFP variant differs from the PGA version (e.g., MC68LC302RC20), which offers full emulation support but larger footprint. The MC68LC302CPU20CT's TQFP construction prioritizes board space savings and manufacturability in high-volume embedded systems.