The coil power supply product such as passive stylus pens and RFID cards do not require a battery to operate but harvest power from the magnetic coil. Thus, power-on consumption is critical to such a product. 

Power-on consumption is the power consumption after MCU is powered on and before Flash memory is initialized. In a coil power supply system, the power that comes from the coil charges the capacitor. Before the capacitor is charged to the operating voltage, if the MCU consumes too much power, the capacitor voltage will drop, causing the system to be in reset status and unable to work normally. Therefore, the MUG51 features low power at 200 μA to meet the requirements of the coil power supply system.

The NuMicro MUG51 series is a Flash embedded 1T 8051-based low-power microcontroller. It runs up to 7.3728 MHz with 16 Kbytes embedded Flash memory, 1 Kbytes embedded SRAM, 4 Kbytes Flash loader memory (LDROM), 1.8V to 5.5V operating voltage, and -40°C to 105°C operating temperature. Its low-power feature makes it suitable for a battery-free device that harvests power from the coil's magnetic field.