NXP Semiconductors MC68331CAG20

Overview

MC68331CAG20 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 20 MHz system clock, supports 32.768-kHz crystal-based low-power timing, and delivers fully static operation for deterministic control in industrial motion systems.

For engineers reviewing the MC68331CAG20 datasheet, MC68331CAG20 pinout, MC68331CAG20 application, or MC68331CAG20 equivalent, this page provides verified technical context, validated pin functions, confirmed peripheral capabilities, and real-world implementation guidance for embedded motor control, PLC I/O modules, and deterministic real-time automation systems.

Technical Context

The MC68331CAG20 implements a modular architecture with CPU32 core, SIM, GPT, and QSM interconnected via a standardized 24-bit address/16-bit data intermodule bus (IMB). Its SIM provides programmable chip selects, watchdog timer, clock monitor, and external bus interface supporting 16-bit data transfers.

GPT includes two 16-bit free-running counters, three input capture channels, four output compare channels, and dual PWM outputs. QSM integrates SCI (UART) and QSPI with 80-byte RAM and automatic transfer queuing - all accessible through shared PQFP pins with configurable I/O roles.

Key Specifications

Pinout & Package

MC68331CAG20 uses a 132-pin Plastic Quad Flat Package (PQFP) with 0.65 mm lead pitch. Pin functions are multiplexed across dedicated port groups (PQS, PG, PC, PF, PE) and system control signals.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC68332CAG20, MC68331CAG20 provides identical timing determinism and pin compatibility at lower gate count, while MPC5604B shifts focus to automotive networking - making MC68331CAG20 optimal for cost-sensitive industrial motion control where QSM and IMB modularity are essential.

Availability

MC68331CAG20 is available at Aetrix Electronics and suitable for industrial motor control, PLC I/O modules, automated test equipment sequencers, and energy meter communication gateways requiring stable component supply across long-lifecycle deployments.

Supply support for MC68331CAG20 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 industrial and automotive applications before its 2015 acquisition.

The MC68331 product line was designed for deterministic real-time control in factory automation, offering modular peripherals, static operation, and integrated system protection - targeting applications where timing predictability and long-term supply stability are critical.

FAQ

What is the maximum operating frequency of the MC68331CAG20?

The MC68331CAG20 is rated for a maximum system clock frequency of 20 MHz. This specification is validated across the full –40°C to +85°C temperature range and enables instruction cycle times as fast as 50 ns. The device achieves this using an internal PLL synchronized to a 32.768-kHz crystal reference, and its fully static design ensures reliable operation even when the clock is gated or stopped during low-power modes.

Does the MC68331CAG20 support external memory expansion?

Yes, the MC68331CAG20 supports external memory expansion via its 24-bit address bus (ADDR[23:0]) and 16-bit data bus (DATA[15:0]). It includes eleven programmable chip-select outputs (CS[10:0]) with individually configurable base addresses and timing options, allowing direct interfacing with SRAM, flash, EPROM, and peripheral ICs without external address latches or glue logic.

What serial communication interfaces does the MC68331CAG20 integrate?

The MC68331CAG20 integrates a Queued Serial Module (QSM) that provides both SCI (asynchronous UART) and QSPI (synchronous serial peripheral interface) functionality. SCI supports standard UART features including modulus baud rate generation and parity; QSPI includes an 80-byte internal RAM buffer and supports up to 16 automatic transfers per queue - all accessible through the same PQS[7:0] pin group with software-configurable function assignment.

How does the MC68331CAG20 handle power management in low-power applications?

The MC68331CAG20 implements low-power operation through its fully static CPU32 core and dedicated LPSTOP instruction. When executed, LPSTOP stops the system clock while preserving register and memory contents, reducing power consumption to standby levels. Clock resumption is triggered by any enabled interrupt or external reset - making it suitable for battery-backed controllers and intermittent-scan sensor nodes where deterministic wake-up timing is required.

Is the MC68331CAG20 pin-compatible with other members of the MC6833x family?

Yes, the MC68331CAG20 shares identical pinout and electrical characteristics with other 132-pin PQFP variants in the MC6833x family, including MC68331CFC20 and MC68332CAG20. All share the same 132-pin footprint, signal assignments, and drive strength specifications - enabling drop-in replacement where functional differences (e.g., QSM enhancements in MC68332) are not utilized in the target application.