The wide supply voltage ranges from 1.8V to 5.5V, and operating temperature ranges from -40℃ to 105℃; NuMicro M251/M252 Series provides rich package types from 20-pin to 128-pin, and five power modes for different operating scenarios. Integrating RTC with independent VBAT to support low power mode, low power ΜART supports transmission rates up to 9600 bps in power-down mode to make power management much more efficient in battery-powered devices. NuMicro M251/252 Series provides 138 μA/MHz in normal run mode. The power-down mode current with RTC is down to 2.5μA, and the Deep power-down current is less than 1.4 μA.

NuMicro M251/ M252 Series supports powerful and rich peripherals, such as Programmable Serial I/O (PSIO), up to six pins of Voltage Adjustable Interface (VAI), External Bus Interface (EBI), Universal Serial Control Interface (USCI), QSPI, SPI/I²S, I2C, Smart Card Interface (ISO-7816-3), Watchdog timer, RTC, and up to 24 channels of PWM. Those peripherals make it highly suitable for connecting comprehensive external modules. For high-performance analog features, it integrates up to a 16-channel 12-bit 880 kSPS SAR ADC to sample the sensor data without delay, one Operational Amplifier (OPA) to amplify small signal for motor control, built-in five levels of internal voltage reference to provide precise voltage to ADC and ACMP, one 12-bit 1 MSPS voltage type DAC, and two rail-to-rail analog comparator (ACMP) to enhance product competitivity and reduce both external components and form factor.

NuMicro M251/ M252 Series provides up to eight channels of Nuvoton Patented Programmable Serial I/O (PSIO), accompany with PDMA hardware could realize several proprietary serial interfaces, such as DMX512, HDQ, 1-wire, Microwire, and programmable encoder, no matter the standard interface or proprietary interface can be realized by PSIO interface, which can not only adding the feasibility of proprietary interface but also shorten the complexity of program but to ease the loading from CPU.

To protect customer’s intellectual property, NuMicro M251/M252 Series provides several mechanisms, by using flash lock bit can prevent the program from being read out by an external programmer, built-in one eXecute-Only-Memory (XOM) region and four Memory Protection Unit (MPU) to protect critical codes, and one Tamper detection pin to detect the state transition status. NuMicro M251/M252 Series also equipped with 96-bit UID (Unique Identification) and 128-bit UCID (Unique Customer Identification). Besides, Nuvoton provides a safety library that can be compliant with the IEC-60730 requirement for Class B safety function to raise safety function for customers’ end products.

Moreover, Nu-Link and Nu-Link-2-Pro debuggers are available for evaluation and product development. Third-Party IDEs such as Keil MDK, IAR EWARM, and NuEclipse IDE with GNU GCC compilers are also supported. The latest NuTool-Code-Generator is available to generate the initial program automatically.