The NuMicro MG51 series brings enhanced I/O flexibility, analog precision, and EMI protection to industrial applications.
Nuvoton Technology recently released its NuMicro MG51 series, a new line of industrial-grade 8-bit microcontrollers (MCUs) based on a high-performance 1T-8051 core.
Supporting up to 12-channel PWM outputs, the new series can be useful for industrial automation and small motor applications. Image (modified) used courtesy of Nuvoton
Designed for applications such as home appliances, LED lighting, motor control, and industrial automation, the MG51 series combines a wide operating range with strong electromagnetic immunity and an array of peripheral features to support real-time control and communication tasks in electrically noisy environments.
MCU Architecture and Peripheral Features
The heart of the MG51 series (datasheet linked) is a fully static 1T-8051 architecture that can execute instructions at up to 24 MHz. Available in compact 20-pin packages (TSSOP and QFN), the devices offer up to 32 KB of flash memory, 1 KB of auxiliary RAM (XRAM), 256 bytes of on-chip RAM, and 4 KB of loader memory (LDROM) for bootloading via in-system programming (ISP). Memory security is reinforced with a 96-bit unique ID, a 128-bit customer ID, and a 128-byte software protection ROM.
The MG51 integrates a rich set of peripherals meant for control-centric applications, including four 16-bit timers, with Timer 2 supporting three-channel input capture and Timer 3 configurable for baud rate generation. For communications, the MCU supports up to two UARTs with automatic address recognition and frame error detection, one I2C interface supporting master/slave modes and 400 kbps operation, and one SPI interface configurable as either master or slave.
Block diagram of the NuMicro MG51. Image used courtesy of Nuvoton
To support real-time sensing and actuation, the MG51 series includes a 12-bit SAR ADC with up to eight external input channels and one internal bandgap reference channel that achieves 500 kSPS throughput. The analog subsystem allows PWM-triggered sampling for tight control loops. The MCU also offers six PWM channels with up to 24-MHz resolution, support for complementary outputs, dead-time insertion, and tri-state control for each pin.
On the digital I/O front, the MG51 provides 18 general-purpose I/O pins supporting Schmitt trigger inputs, four configurable modes (quasi-bidirectional, push-pull, open-drain, and high-impedance input), and edge/level-triggered interrupts on all pins. Nuvoton reports high EMI performance, achieved with ±7 kV HBM ESD, ±4.4 kV EFT immunity, and ±200 mA latch-up tolerance.
ESD and EFT Immunity in Embedded Systems
Electrostatic discharge (ESD) and electrical fast transients (EFT) are two prevalent forms of electromagnetic disturbances that can impair or destroy sensitive electronics. ESD results from the sudden flow of static electricity between two objects at different potentials, often triggered by human contact or charged surfaces. It can inject thousands of volts into a circuit in a fraction of a second. EFT, on the other hand, arises from rapid transients caused by switching inductive loads (e.g., relays, motors, or power supplies) and typically manifests as bursts of high-frequency pulses.
In microcontroller-based systems in industrial and appliance applications, unmitigated ESD and EFT events may lead to erratic behavior or permanent damage. To guarantee operational integrity, developers require both circuit-level and architectural mitigation techniques. These include placing transient voltage suppression (TVS) diodes on I/O lines, using proper PCB grounding and shielding, designing with sufficient spacing between sensitive traces, and isolating power domains.
ESD and EFT protection on an RS-485 transceiver board. Image used courtesy of Texas Instruments
On-chip strategies for immunity often include ESD clamping circuits, robust I/O driver designs, and carefully engineered substrate layouts. Regulatory and industry standards such as IEC 61000-4-2 for ESD and IEC 61000-4-4 for EFT provide test methodologies and threshold levels to evaluate device resilience. Compliance with these standards is, therefore, necessary for manufacturers aiming to deploy products in commercial and industrial environments where electrical noise is routine.
Designers must also be aware of the cumulative effects of repeated transient exposure, which may degrade device reliability over time. As such, integrating noise-tolerant components and validating designs under worst-case conditions are necessary steps in developing resilient embedded systems.
Focused Performance for Embedded Control
Nuvoton’s MG51 series offers an attractive blend of affordability and robustness, resulting in a solution for entry-level and moderately complex embedded applications. Development support is currently available through Nuvoton’s NuMaker evaluation board and comprehensive toolchain compatibility with Keil, IAR, and NuEclipse SDCC. Sample and production quantities are now available through Nuvoton’s distribution partners.
