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.