EFM8UB1 8-bit MCUs Silicon Labs EFMU8B1 8-bit MCUs are multipurpose microcontrollers with USB feature set in small packages. These MCUs integrate USB peripheral interface, charger detect circuit, 8kV ESD protection, and high-speed communication interfaces in one package. Digital peripherals include two UART, SPI, SPI/I2C master/slave, and I2C slave. These MCUs feature one 12-bit ADC and two analog comparators with adjustable reference. The Precision analog and efficient 8051 core with up to 50MHz frequency make these MCUs optimal for the embedded applications. Features include up to 22 multifunction I/O pins, 5V input LDO regulator, five 16-bit timers, and priority crossbar for flexible pin mapping. Applications include USB I/O controls, dongles, high-speed communication bridge, consumer electronics, and medical equipment.