MS51FB9AE 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 TSSOP20. https://www.campuscomponent.com/products/nuvoton-ms51fb9aea1ed/2208614000001841334