A Self-adaption Power Switch Circuit For Battery Supplyed NFC Chip

NFC chip can capture power from antenna when it is in magnetic field. At the same time, NFC chip may also be powered by battery at IoT application, and it needs to shutdown battery supply to save battery energy, which makes it complex for power switch architecture. This paper presents an architecture and circuit design for NFC chip to switch power between battery and magnetic field inducing energy. An offchip 1 uF capacitor is used to filter the magnetic field power swing in wireless communication time. This circuit also collects the magnetic field inducing energy and output a current as large as 5mA (3.3V) for other IoT chip or charging battery.