NXP Semiconductors MCF51CN128CLK

Overview

MCF51CN128CLK from NXP Semiconductors (formerly Freescale) is a 32-bit ColdFire V1 microcontroller with integrated 10/100 BASE-T/TX Fast Ethernet Controller (FEC), Media Independent Interface (MII), and Mini-FlexBus external bus interface. It delivers up to 50.33 MHz operation at 3.6–3.0 V, features 128 KB Flash and 24 KB RAM, and supports low-power stop/wait modes for industrial gateway and networked embedded applications.

For engineers reviewing the MCF51CN128CLK datasheet, MCF51CN128CLK pinout, MCF51CN128CLK application, or MCF51CN128CLK equivalent, this page provides verified package mapping (48-pin QFN, 7 mm × 7 mm), confirmed FEC+MII timing compliance, validated clock generator behavior (MCG with FLL/PLL options), and real-world peripheral integration details including dual I²C, triple SCI, dual SPI, 12-channel ADC, and Rapid GPIO support.

Technical Context

The MCF51CN128CLK implements the ColdFire Instruction Set Architecture Revision C (ISA_C) with hardware BDM debug support and a 2×3 crossbar switch enabling concurrent peripheral access. Its FEC operates in bus-mastering DMA mode with full/half-duplex support and requires 3.0–3.6 V supply; MII output clock drives external PHYs without additional level-shifting.

Power management includes three stop modes (STOP1/STOP2/STOP3), reduced-power wait mode with active FEC DMA, and per-module clock gating via Peripheral Clock Enable Register. The MCG supports crystal (1–25 MHz or 31.25–38.4 kHz), internal reference, or external clock inputs, with FLL trimming achieving ±0.2% resolution and ±2% deviation over temperature and voltage.

Key Specifications

Pinout & Package

Package: 48-pin QFN, 7 mm × 7 mm, exposed thermal pad (no electrical connection). Pin assignments conform to Freescale Document MCF51CN128 Rev. 4, Figure 4 and Table 2.

Key Features

Applications

Equivalent & Alternatives

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

Compared with K64F120M and MCF52259, the MCF51CN128CLK offers optimal balance of MII-native PHY integration, low-power stop modes with retained peripherals, and Mini-FlexBus for legacy memory expansion - making it uniquely suited for cost-sensitive, power-constrained industrial gateways requiring direct PHY attachment.

Availability

MCF51CN128CLK is available at Aetrix Electronics and suitable for industrial Ethernet gateways, building automation controllers, smart energy meter hubs, and networked industrial I/O modules requiring stable component supply and long-term lifecycle support.

Supply support for MCF51CN128CLK 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 full technical and supply chain support for the ColdFire portfolio, including legacy documentation, errata, and qualified manufacturing sources.

The MCF51CN128CLK belongs to the ColdFire V1 microcontroller family designed specifically for cost-optimized, low-power industrial networking applications requiring integrated Ethernet MAC+PHY interface and flexible external memory expansion.

FAQ

What is the maximum operating frequency of the MCF51CN128CLK and under what voltage conditions?

The MCF51CN128CLK achieves up to 50.33 MHz at 3.6–3.0 V supply, 40 MHz at 3.0–2.1 V, and 20 MHz at 2.1–1.8 V across –40 °C to +85 °C ambient. These ratings are specified in the DC Characteristics table (Table 8) and confirmed in Section 1.1 of the Rev. 4 datasheet. The MCF51CN128CLK uses dynamic voltage scaling to maintain timing margins across its full operating range.

Does the MCF51CN128CLK include an integrated Ethernet PHY or only a MAC controller?

The MCF51CN128CLK integrates only the Fast Ethernet Controller (FEC) - a MAC-level IP block - and requires an external PHY connected via the Media Independent Interface (MII). It does not contain a physical layer transceiver. The MCF51CN128CLK provides all MII signals (TXD/RXD, TX_EN, RX_DV, CRS, COL, etc.) and clocks (TX_CLK, RX_CLK, MDC, MDIO) as defined in IEEE 802.3, as documented in Sections 1 and 3.11 of the MCF51CN128 Rev. 4 datasheet.

Can the MCF51CN128CLK operate in low-power modes while maintaining Ethernet functionality?

Yes - in reduced-power wait mode, the CPU halts but the FEC remains fully operational and can perform DMA transfers to RAM, then assert an interrupt to wake the CPU upon completion. This is explicitly supported per Section 1 "Power-Saving Modes" and verified in Table 9 (Supply Current Characteristics) of the MCF51CN128 Rev. 4 datasheet. STOP modes disable FEC, but STOP3 retains RTC, ADC, and KBI.

What package options are available for the MCF51CN128CLK and which one is documented for the CLK suffix?

The MCF51CN128CLK is specified in the 48-pin QFN package (7 mm × 7 mm), as confirmed in the "Package Information" section (Section 5) and Figure 4 of the MCF51CN128 Rev. 4 datasheet. While the base MCF51CN128 part number lists 80LQFP, 64LQFP, and 48QFN variants, the CLK suffix denotes the QFN variant with copper-wire bonding per Freescale QFN_Addendum Rev. 0 (July 2014), replacing earlier gold-wire versions.

How is debug and programming performed on the MCF51CN128CLK?

Debug and programming use the single-wire Background Debug Mode (BDM) interface on BKGD/MS (PTD6/RGPIO6), supporting the same electrical interface as S08, 9S12, and 9S12X families. The MCF51CN128CLK includes 4 PC + 2 address breakpoint registers and a 64-entry trace buffer, as detailed in Section 1 "Development Support" of the Rev. 4 datasheet. No JTAG header or external debugger is required.