MCF51MM256CMB - 50MHz ColdFire V1 256KB Flash MCU | NXP
MPN: MCF51MM256CMB ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $9.8 | $9.80 |
| 10 | $9.2 | $92.00 |
| 100 | $8.6 | $860.00 |
| 500 | $8.05 | $4,025.00 |
| 1,000 | $7.4 | $7,400.00 |
MCF51MM256CMB Overview
What is a ColdFire V1 microcontroller? ColdFire is a 32-bit RISC instruction-set architecture originally developed by Freescale (now NXP) as a successor to the 68k family. The V1 core is the smallest and lowest-power ColdFire implementation, providing 32-bit processing capability with Thumb-like code density. MCUs in this category serve as system controllers in metering, motor control, and consumer products where deterministic 32-bit performance is required without the overhead of higher-tier Cortex-M cores.
Key features include 256 KB Flash program memory, 32 KB SRAM, an on-chip LCD driver, 16-bit SAR ADC, two analog comparators, and a multi-channel timer/PWM module. The device integrates a real-time clock, multiple low-power modes (Wait, Stop, Low-Power Run), and a flexible 48-pin I/O count. The ColdFire V1 core delivers 50 MHz operation from a 1.8 V to 3.6 V supply while maintaining static current consumption under 5 uA in Stop mode with RTC.
The MCF51MM256's architecture combines a V1 core with a peripheral set optimized for single-phase electricity meters: the ADC plus analog front end enables accurate active/reactive power and RMS voltage/current measurement, while the integrated LCD module can drive up to 8x40 segments typical for residential meter displays. The chip supports background-debug mode (BDM) and JTAG for development, and includes a hardware cryptographic acceleration unit for secure metering applications.
Typical applications include single-phase electricity meters, smart energy monitors, HVAC control panels, low-end motor controllers, and consumer appliances with LCD interfaces. The integrated analog chain (16-bit ADC + PGA + comparators) simplifies BOM in cost-sensitive metering designs.
When designing with the MCF51MM256, choose an external 32.768 kHz crystal for the RTC and ensure the BDM/JTAG header is accessible for firmware development. Decouple each VDD/VSS pair with a 100 nF ceramic placed within 3 mm of the ball, and provide a 4.7 uF bulk cap near the package to support the LCD charge pump during display refresh.
Drop-in alternatives for MCF51MM256CMB — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with MCF51MM256CMB (same form factor and footprint) — differing in Core Architecture, Mounting Type, Supply Voltage, Package, Program Memory Size.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MCF51MM256VML
✅ Drop-In✓ In Stock
$9.2 / Unit
View Datasheet →MCF51MM256CLB
✅ Drop-In📋 Reference alternative (not in catalog)
MCF51MM256CMD
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
MCF51MM256CMB Maximum Ratings & Electrical Characteristics
| Core Architecture | ColdFire V1 (32-bit RISC) |
| Maximum Clock Frequency | 50 MHz |
| Program Memory (Flash) | 256 KB (256K x 8) |
| RAM Size | 32 KB (32K x 8) |
| Number of I/O | 48 |
| Package / Case | 81-MAPBGA (10x10 mm) |
| Oscillator Type | External |
| Supply Voltage | 1.8 V to 3.6 V |
| Operating Temperature | -40 C to +85 C |
| Peripherals | LCD, 16-bit SAR ADC, Analog Comparators, PWM/Timer, RTC |
| Connectivity | I2C, SCI (UART), SPI, I2S |
| Data Converters | 16-bit SAR ADC, 12-bit DAC |
| Program Memory Type | FLASH |
| Mounting Type | Surface Mount |
| MSL Level | 3 (per JEDEC J-STD-020) |
| RoHS Status | Compliant |
MCF51MM256CMB Pin Configuration
| Pin A1 | VDD — Power supply (1.8 V to 3.6 V) |
| Pin A2 | VSS — Ground |
| Pin A3 | PTB0 — Port B bit 0 / ADC channel |
| Pin A4 | PTB1 — Port B bit 1 |
| Pin A5 | PTB2 — Port B bit 2 |
| Pin A6 | PTB3 — Port B bit 3 |
| Pin A7 | PTB4 — Port B bit 4 |
| Pin A8 | PTB5 — Port B bit 5 |
| Pin A9 | PTB6 — Port B bit 6 |
| Pin B1 | PTA0 — Port A bit 0 |
| Pin B2 | PTA1 — Port A bit 1 |
| Pin B3 | PTA2 — Port A bit 2 |
| Pin B4 | PTA3 — Port A bit 3 |
| Pin B5 | PTA4 — Port A bit 4 |
| Pin B6 | PTA5 — Port A bit 5 |
| Pin B7 | PTA6 — Port A bit 6 |
| Pin B8 | PTA7 — Port A bit 7 |
| Pin B9 | PTC0 — Port C bit 0 |
| Pin C1 | PTC1 — Port C bit 1 |
| Pin C2 | PTC2 — Port C bit 2 |
| Pin C3 | PTC3 — Port C bit 3 |
| Pin C4 | PTC4 — Port C bit 4 |
| Pin C5 | PTC5 — Port C bit 5 |
| Pin C6 | PTC6 — Port C bit 6 |
| Pin C7 | PTC7 — Port C bit 7 |
| Pin C8 | PTD0 — Port D bit 0 |
| Pin C9 | PTD1 — Port D bit 1 |
| Pin D1 | PTD2 — Port D bit 2 |
| Pin D2 | PTD3 — Port D bit 3 |
| Pin D3 | PTD4 — Port D bit 4 |
| Pin D4 | PTD5 — Port D bit 5 |
| Pin D5 | PTD6 — Port D bit 6 |
| Pin D6 | PTD7 — Port D bit 7 |
| Pin D7 | PTE0 — Port E bit 0 |
| Pin D8 | PTE1 — Port E bit 1 |
| Pin D9 | PTE2 — Port E bit 2 |
| Pin E1 | PTE3 — Port E bit 3 |
| Pin E2 | PTE4 — Port E bit 4 |
| Pin E3 | PTE5 — Port E bit 5 |
| Pin E4 | PTE6 — Port E bit 6 |
| Pin E5 | PTE7 — Port E bit 7 |
| Pin E6 | PTF0 — Port F bit 0 |
| Pin E7 | PTF1 — Port F bit 1 |
| Pin E8 | PTF2 — Port F bit 2 |
| Pin E9 | PTF3 — Port F bit 3 |
| Pin F1 | PTF4 — Port F bit 4 |
| Pin F2 | PTF5 — Port F bit 5 |
| Pin F3 | PTF6 — Port F bit 6 |
| Pin F4 | PTF7 — Port F bit 7 |
| Pin F5 | LCD0 — LCD segment driver |
| Pin F6 | LCD1 — LCD segment driver |
| Pin F7 | LCD2 — LCD segment driver |
| Pin F8 | LCD3 — LCD segment driver |
| Pin F9 | LCD4 — LCD segment driver |
| Pin G1 | LCD5 — LCD segment driver |
| Pin G2 | LCD6 — LCD segment driver |
| Pin G3 | LCD7 — LCD segment driver |
| Pin G4 | LCD8 — LCD segment driver |
| Pin G5 | LCD9 — LCD segment driver |
| Pin G6 | LCD10 — LCD segment driver |
| Pin G7 | LCD11 — LCD segment driver |
| Pin G8 | LCD12 — LCD segment driver |
| Pin G9 | LCD13 — LCD segment driver |
| Pin H1 | VDDA — Analog supply |
| Pin H2 | VSSA — Analog ground |
| Pin H3 | VREFH — ADC reference high |
| Pin H4 | VREFL — ADC reference low |
| Pin H5 | EXTAL — External crystal input |
| Pin H6 | XTAL — External crystal output |
| Pin H7 | RESET — Reset input (active low) |
| Pin H8 | BKGD — Background Debug Mode |
| Pin H9 | VSS — Ground |
| Pin J1 | TCLK — Timer clock input |
| Pin J2 | IRQ — External interrupt request |
| Pin J3 | NC — Not connected (per datasheet) |
| Pin J4 | NC — Not connected (per datasheet) |
| Pin J5 | NC — Not connected (per datasheet) |
| Pin J6 | NC — Not connected (per datasheet) |
| Pin J7 | NC — Not connected (per datasheet) |
| Pin J8 | NC — Not connected (per datasheet) |
| Pin J9 | NC — Not connected (per datasheet) |
Typical Applications
MCF51MM256CMB is suitable for 6 applications: Single-Phase Electricity Meter, Smart Energy Monitor / Home Energy Display, HVAC Control Panel, Low-End Motor Controller, Consumer Appliance with LCD UI, Industrial Sensor / Data Logger.
Single-Phase Electricity Meter
The MCF51MM256CMB was designed from the ground up for single-phase residential electricity meters, and the integration pays off directly here. Its on-chip 16-bit SAR ADC with programmable gain amplifier, combined with two analog comparators, lets designers measure shunt-derived current and divider-derived voltage without an external metering ASIC - cutting BOM cost and PCB area. The integrated LCD driver (up to 8x40 segments per the NXP MCF51MM256 datasheet) drives the meter's display directly, while the 50 MHz ColdFire V1 core executes real-time active/reactive power and RMS calculations with deterministic timing. The 256 KB Flash accommodates metering firmware stacks plus tamper-detection logic, and the 32 KB SRAM buffers measurement samples and rolling energy data. Low-power modes (Wait, Stop, Low-Power Run) with sub-5 uA Stop current enable battery-backed meter endpoints that retain RTC time across line-power outages.
Recommended
Smart Energy Monitor / Home Energy Display
Smart plug and home energy monitor products benefit from the MCF51MM256CMB's metering-grade analog front end and integrated LCD controller. Designers can read CT-based current sensors or shunt resistors directly into the 16-bit ADC with the on-chip PGA, eliminating an external analog front-end IC. The ColdFire V1 core at 50 MHz handles RMS and power-factor calculations in real time, while the 32 KB SRAM buffers rolling energy data for non-volatile storage. The integrated LCD driver supports low-cost monochrome segment displays common in wall-mounted home energy displays, and the part's 1.8 V to 3.6 V supply range matches USB- or battery-powered designs. I2C and SPI interfaces connect to wireless modules (Wi-Fi, Zigbee, Sub-GHz) for cloud connectivity, while the RTC timestamps consumption events for time-of-use billing.
Recommended
HVAC Control Panel
The MCF51MM256CMB fits HVAC control panels that need a 32-bit core, an LCD for the user interface, and robust analog inputs for temperature and pressure sensors. The ColdFire V1 core executes PID loops for compressor and fan control at 50 MHz with deterministic interrupt latency. The integrated 16-bit ADC reads thermistor, RTD, and pressure transducer signals directly, while the on-chip comparators enable over-temperature and over-current protection without external analog parts. The LCD driver simplifies thermostat display boards by removing the need for a separate LCD controller IC. With 256 KB Flash, designers can fit full HVAC state machines plus Modbus or BACnet application stacks, and 48 I/O pins accommodate relay drivers, triac interfaces, and keypad scanning. The -40 C to +85 C operating range covers basement and rooftop control environments.
Recommended
Low-End Motor Controller
Low-end brushless DC and stepper motor drives use the MCF51MM256CMB to combine a 32-bit control core with an integrated ADC and PWM channels. The ColdFire V1 core executes field-oriented control or trapezoidal commutation algorithms in real time, while the on-chip PWM modules drive the gate drivers directly. Back-EMF and current-shunt feedback enter the 16-bit ADC and comparators, providing the over-current and stall-protection loops. The 256 KB Flash accommodates lookup tables, PI tuning, and fault-handling code; the 32 KB SRAM retains diagnostic logs. The 81-MAPBGA package keeps the controller compact for integrated motor control PCBs, while the 1.8 V to 3.6 V supply simplifies design when powered from a single 3.3 V rail. The integrated RTC supports scheduled on/off cycles for pumps and fans.
Recommended
Consumer Appliance with LCD UI
Consumer appliances such as washing machines, microwave ovens, and induction cooktops benefit from the MCF51MM256CMB's combination of LCD driver, 16-bit ADC, and 32-bit core. The ColdFire V1 core runs appliance state machines and user-interface logic, while the LCD driver directly drives the segment display typically mounted on the front panel - eliminating a discrete LCD controller. The on-chip ADC reads thermistor inputs for cooking or wash-temperature regulation, and the analog comparators handle over-temperature and zero-cross detection for triac-driven heating elements. 256 KB Flash accommodates menu structures, fault logs, and field-updatable firmware via UART bootloader. The wide 1.8 V to 3.6 V supply and -40 C to +85 C temperature range suit the appliance operating environment.
Recommended
Industrial Sensor / Data Logger
Industrial sensor heads and data loggers use the MCF51MM256CMB when they need a 32-bit core, on-chip ADC, and RTC in a single BGA. The ColdFire V1 core at 50 MHz executes sensor linearization, statistical filtering, and SD-card write streams, while the integrated 16-bit ADC reads multiple sensor channels with PGA gain. The on-chip RTC provides accurate timestamps for logged events, and the RTC domain retains time across power cycles in Stop mode (<5 uA). The 256 KB Flash fits loggers with local configuration storage and Modbus RTU stacks, while 32 KB SRAM buffers incoming samples before flushing to non-volatile storage. The 81-MAPBGA (10x10 mm) footprint suits compact industrial enclosures, and the -40 C to +85 C temperature range covers outdoor and factory-floor installations.
Recommended
Recommended Products Summary
Engineering reference data for MCF51MM256CMB — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MCF51MM256VML | MCF51MM256CLB | MCF51MM256CMD |
|---|---|---|---|---|
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Package | 81-MAPBGA (10x10 mm) | 81-LQFP (different land pattern - PCB rework required) | 81-MAPBGA (same as CMB) | 81-MAPBGA (same as CMB) |
| Core | ColdFire V1 | ColdFire V1 (same) | ColdFire V1 (same) | ColdFire V1 (same) |
| Max CPU Clock | 50 MHz | 50 MHz | 50 MHz | 50 MHz |
| Flash Memory | 256 KB | 256 KB | 256 KB | 256 KB |
| SRAM | 32 KB | 32 KB | 32 KB | 32 KB |
| Supply Voltage | 1.8 V to 3.6 V | 1.8 V to 3.6 V | 1.8 V to 3.6 V | 1.8 V to 3.6 V |
| Operating Temperature | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
| Packaging Form | Tray | Tray | Tray | Tape and Reel |
| Distinctive Variant | Standard power-on default | LQFP-package variant | Low-power-mode boot default | Tape & reel packaging option |
Key Differentiators
- On-chip metering-grade analog front end (vs MCF51AC256 (ColdFire V1 general-purpose MCU))
- Integrated LCD driver for segment displays (vs MCF51JE128 (industrial Ethernet MCU))
- Sub-5 uA Stop-mode current with RTC retention (vs MC9S08QE128 (8-bit HCS08 metering MCU))
Design Notes
Place one 100 nF X7R ceramic decoupling capacitor within 3 mm of every VDD/VSS ball pair of the 81-MAPBGA, and add a single 4.7 uF X5R bulk cap near the package. The integrated LCD charge pump draws pulsed current during segment refresh - insufficient bulk capacitance will cause display contrast modulation visible as flicker. Route the analog VREFH/VREFL traces as a guarded differential pair away from digital switching signals.
The 81-MAPBGA (10x10 mm) uses a 1.0 mm ball pitch - follow IPC-7351 land pattern recommendations with NSMD pads and a 0.4 mm solder-mask opening. Provide a via-in-pad or microvia escape pattern on inner layers for clean ground returns, and dedicate one solid inner plane under the BGA as the ground reference for the analog front end. Keep the EXTAL/XTAL traces short and symmetric to minimize oscillator jitter that affects ADC timing accuracy.
Do not connect the BKGD (Background Debug Mode) pin to VDD through a pull-up without consulting the NXP MCF51MM256 Reference Manual - the BDM handshake requires the pin to be open-drain or tri-state at reset. Forgetting to disable the on-chip voltage regulator (if used) before entering Stop mode can leave the RTC domain partially powered and inflate standby current. Always include a 32.768 kHz external crystal on EXTAL/XTAL if RTC accuracy matters, because the internal oscillator is not precise enough for time-of-use metering.
Estimated: when sampling the 16-bit SAR ADC at the maximum rate (~200 kSps) while simultaneously driving the LCD charge pump and PWM channels, switching noise on VDD can alias into ADC results. Place an RC low-pass (10 ohm + 10 uF) between the digital and analog VDD planes if ADC ENOB degrades more than 1 bit under load. Use the on-chip PGA gain setting that lets the input signal span at least 80 percent of the ADC full scale to maximize SNR.
Compliance Information
RoHS compliance per NXP product page and DigiKey parametric listing. Not AEC-Q100 qualified - this is an industrial/consumer metering MCU, not an automotive grade. Halogen-free status not explicitly stated in retrieved data. MSL 3 per JEDEC J-STD-020 moisture sensitivity classification.