As a leading supplier of 8051 microcontrollers ( MCUs ) , Nuvoton offers a variety of products with the best performance critical to the success of consumers and industrial products. The 8-bit MCU supports pin-compatible with traditional 12 T 8051 , wide operating voltage ( 2.4V ~ 5.5V ) , industrial temperature ( -40 ℃ ~ 85 ℃ ) , 22.1184 internal oscillator ( 1 % accuracy at 25 ℃, 5V ) , Data Flash configurable, a rich set of I/O such as PWM, ADC, UART, SPI, I²C, comparator, ISP, ICP, and high noise immunity ( 8 kV ESD, 4 kV EFT ) , and provides small compact package such as TSSOP20 and QFN20 . It is one of the best choice of 8051 MCUs.