NXP Semiconductors MCF51EM256CLL

Overview

MCF51EM256CLL from NXP Semiconductors (formerly Freescale) is a 32-bit ColdFire V1 RISC microcontroller with integrated 256 KB flash, 16 KB RAM, ultra-low-power IRTC, 16-bit SAR ADC, LCD driver, and dual analog comparators. It operates up to 50.33 MHz at 2.5–3.6 V and supports three SCI, three SPI, and I²C interfaces. Designed for battery-powered industrial HMI and metering applications requiring calendar-aware real-time operation and segment LCD display.

For engineers reviewing the MCF51EM256CLL datasheet, MCF51EM256CLL pinout, MCF51EM256CLL application, or MCF51EM256CLL equivalent, this page delivers verified technical context, validated 100-pin LQFP pin mapping, confirmed low-power run/stop mode behavior, and real-world substitution guidance - all grounded in the Rev.3 Advance Information datasheet and official package documentation.

Technical Context

The MCF51EM256CLL implements the ColdFire V1 core (ISA_C + MAC), delivering 32-bit integer arithmetic and 16×16±32 multiply-accumulate operations. Its system architecture integrates two independent flash arrays supporting concurrent execution and robust firmware updates, plus an independent power domain for the IRTC with battery-backed operation and tamper detection.

Peripherals include four 16-bit ADC modules (16 single-ended/4 differential channels), programmable delay block (PDB) for synchronized sampling, two PRACMP analog comparators with edge-selectable interrupts, and a flexible LCD controller driving up to 288 segments. Clocking combines dual crystal oscillators (XOSC1 for IRTC, XOSC2 for CPU) and an internal clock source (ICS) with FLL-based frequency multiplication and ±0.5% typical accuracy over voltage and temperature.

Key Specifications

Pinout & Package

Package: 100-pin LQFP, 14 mm × 14 mm, RoHS-compliant. Pin functions are multiplexed across up to four alternate roles per pin; default assignments are active unless explicitly reconfigured via SIM and port control registers.

Key Features

Applications

Equivalent & Alternatives

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

Compared with Kinetis KL27Z128VLH4 and MCF51JM128CLK, the MCF51EM256CLL uniquely combines 256 KB flash, integrated 288-segment LCD driver, and battery-backed IRTC calendar - making it irreplaceable in legacy ColdFire-based metering and HMI platforms requiring long-term software continuity and display integration.

Availability

MCF51EM256CLL is available at Aetrix Electronics and suitable for smart energy metering, industrial HMI panels, portable medical instruments, and battery-powered data loggers requiring stable component supply, long lifecycle support, and qualified cold-temperature operation (–40°C to +85°C).

Supply support for MCF51EM256CLL 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 continues to support the ColdFire portfolio for industrial and metering applications requiring long-term reliability and deterministic real-time performance.

The MCF51EM256CLL belongs to the ColdFire EM series - designed specifically for ultra-low-power, mixed-signal embedded systems integrating precision analog, real-time clocking, and human interface peripherals in a single SoC.

FAQ

What is the maximum operating frequency of the MCF51EM256CLL and under what conditions?

The MCF51EM256CLL achieves a maximum CPU frequency of 50.33 MHz when powered at 2.5–3.6 V across the –40°C to +85°C temperature range. At lower voltages (1.8–2.5 V), the maximum frequency reduces to 20 MHz. This specification is confirmed in Section 1.3.1 of the Rev.3 datasheet and applies directly to the MCF51EM256CLL in its 100-pin LQFP package.

Does the MCF51EM256CLL support true hardware debugging, and how is it implemented?

Yes, the MCF51EM256CLL includes an integrated Background Debug Module (BDM) compliant with ColdFire DEBUG_Rev_B+, accessible via the BKGD/MS pin (PTC2). This single-wire interface supports real-time debugging, six hardware breakpoints, and on-chip trace buffer - enabling full firmware development and validation without external JTAG adapters. The MCF51EM256CLL's BDM is functionally identical to that used in Freescale's S08 family.

How does the MCF51EM256CLL manage ultra-low-power operation, and what is its lowest current draw?

The MCF51EM256CLL achieves less than 1.3 μA typical current consumption in battery mode with the MCU supply off, thanks to its independent IRTC power domain and dedicated low-leakage circuitry. This state preserves calendar time and allows wake-up via RTC alarm or external pin interrupt. The value is measured and specified in Section 1.3.1 of the Rev.3 datasheet and applies to the MCF51EM256CLL under nominal conditions.

Can the MCF51EM256CLL drive a segment LCD directly, and what is its maximum segment count?

Yes, the MCF51EM256CLL integrates a fully autonomous LCD controller supporting up to 288 segments (8 backplanes × 36 frontplanes) or 160 segments (4 × 40), with internal charge pump and programmable contrast trim. All LCD pins (LCD0–LCD43) are physically present on the 100-pin LQFP package used by the MCF51EM256CLL, eliminating need for external bias generation or driver ICs.

What are the key differences between the MCF51EM256CLL and the MCF51EM256CLK variants?

The MCF51EM256CLL uses a 100-pin LQFP package with full peripheral access (e.g., 16 ADC inputs, 47 total I/O), while the MCF51EM256CLK uses an 80-pin LQFP with reduced pin count (e.g., 12 ADC inputs, 40 I/O) and disabled functions on missing pins. Both share identical core, memory, and electrical specs - but only the MCF51EM256CLL supports the complete feature set documented for the MCF51EM256 series in the Rev.3 datasheet.