MS51XB9AE is embedded with based on 1T 8051-based CMOS microcontroller. runs up to 24 MHz. features 16 K bytes flash. 1 K bytes SRAM. and 4 K bytes loader ROM for the ISP. also equipped with rich peripherals: 2 sets of UART; 1 set of I²C. and 1 set of SPI. 18 GPIO. 8 channels of 12-bit ADC. Watchdog Timer. Window Watchdog Timer and 6*16-bit PWM channel. package is available in QFN20