NXP Semiconductors MCF51AC256AVFUE

Overview

MCF51AC256AVFUE from NXP Semiconductors (formerly Freescale) is a 32-bit ColdFire V1 microcontroller with CAN interface, 256 KB flash, 32 KB SRAM, and 64-pin QFP package operating up to 50.33 MHz at 2.7–5.5 V. It integrates dual analog comparators, 24-channel 12-bit ADC, two FTM modules, SCI/SCI2, SPI1/SPI2, IIC, CRC, and MCG for industrial motor control and automotive body electronics.

For engineers reviewing the MCF51AC256AVFUE datasheet, MCF51AC256AVFUE pinout, MCF51AC256AVFUE application, or MCF51AC256AVFUE equivalent, key selection considerations include CAN 2.0A/B compliance, 64-pin QFP thermal performance at –40°C to 105°C, FTM deadtime insertion for motor gate drive, and RGPIO's CPU-clock-speed I/O toggle capability.

Technical Context

The MCF51AC256AVFUE implements the ColdFire V1 core with ISA_C instruction set, delivering 0.76 DMIPS/MHz from flash and 0.94 DMIPS/MHz from SRAM. Its MCG supports FLL/PLL clock multiplication using external crystal (1–16 MHz) or internal reference, with trimmable 0.2% resolution.

It features two independent flexible timer modules (FTM1/FTM2), each supporting up to 6 channels in input capture, output compare, or edge-/center-aligned PWM modes-with synchronized register load, fault input handling, and hardware ADC triggering. The integrated MSCAN module supports programmable bit rates up to 1 Mbps, five receive buffers with FIFO, and bus-off recovery.

Key Specifications

Pinout & Package

Package: 64-pin QFP, 14 mm × 14 mm, 0.8 mm pitch, RoHS-compliant (Pb-free indicator 'V'). Pinout conforms to Figure 3 in Rev.7 datasheet, with TxCAN/RxCAN on pins 24/25, BKGD/MS on pin 39, RESET on pin 3, and VDD/VSS distributed across corners for power integrity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar microcontroller applications.

Compared with MCF51AC256BVFUE and Kinetis K22FN512VLH12, the MCF51AC256AVFUE uniquely balances CAN integration, deterministic ColdFire real-time performance, and industrial temperature support in a mature, pin-stable 64-QFP footprint-making it optimal for incremental upgrades from MC9S08AC128.

Availability

MCF51AC256AVFUE is available at Aetrix Electronics and suitable for industrial motor control, automotive body electronics, smart energy metering, and medical infusion pumps requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MCF51AC256AVFUE 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

NXP Semiconductors acquired Freescale in 2015 and maintains the ColdFire portfolio for industrial and automotive microcontroller applications requiring deterministic real-time behavior and long-term supply stability.

The MCF51AC256 series belongs to NXP's legacy ColdFire microcontroller line, designed specifically for seamless migration from 8-bit S08 architectures while delivering 32-bit performance, integrated analog, and CAN connectivity for cost-sensitive industrial control.

FAQ

What is the maximum operating frequency of the MCF51AC256AVFUE and under what conditions?

The MCF51AC256AVFUE operates at up to 50.33 MHz across its full supply voltage range of 2.7 V to 5.5 V and temperature range of –40°C to 105°C. This frequency is achievable using the MCG's PLL mode with an external 8 MHz crystal and proper decoupling per Section 2.10 of the Rev.7 datasheet. Performance is validated with 0.76 DMIPS/MHz when executing from flash memory.

Does the MCF51AC256AVFUE support hardware debugging, and what interface is used?

Yes, the MCF51AC256AVFUE includes a single-wire background debug module (BDM) accessible via the BKGD/MS pin (pin 39). It supports real-time debugging with six hardware breakpoints (four PC, one address pair, one data), on-chip trace buffer, and debug visibility bus (VBUS) for program flow analysis-enabling full flash programming and live variable inspection without halting execution.

How many analog-to-digital converter channels does the MCF51AC256AVFUE have, and what is their resolution?

The MCF51AC256AVFUE integrates a 12-bit successive approximation register (SAR) ADC with 24 configurable analog input channels (AD1P0–AD1P23). Conversion results are right-justified and可 formatted in 12-, 10-, or 8-bit modes. The ADC supports asynchronous clocking to minimize noise coupling and auto-compare interrupts for threshold-based event detection without CPU polling.

What is the purpose of the RGPIO feature in the MCF51AC256AVFUE, and how does it differ from standard GPIO?

RGPIO (Rapid General-Purpose Input/Output) provides 16 dedicated pins (e.g., PTE0–PTE7, PTF0–PTF7) connected directly to the ColdFire V1 core's local 32-bit platform bus. Unlike standard GPIO, RGPIO supports sub-cycle I/O toggle, set/clear operations, and atomic bit manipulation-enabling precise timing-critical outputs such as encoder index pulses or strobe signals without software loop overhead.

Can the MCF51AC256AVFUE operate in low-power modes, and which peripherals remain active during stop3 mode?

Yes, the MCF51AC256AVFUE supports three low-power stop modes. In stop3 mode, the CPU and most clocks halt, but selected peripherals-including the RTC, COP watchdog (with LPO clock), ADC, and certain FTM channels-can remain clocked via the peripheral clock enable register (PCER). This enables wake-up from analog events or timer expiry while consuming minimal current, as specified in Section 1.3.1 of the Rev.7 datasheet.