| 摘要 |
A PSU(Power Supply Unit) for a contactless card is provided to stably supply power voltage for operating an RF card even if a magnetic intensity change is generated by a distance between an RFID(Radio Frequency IDentification) reader and the RF card, or data transfer. A voltage rectifier(110) generates power voltage for operating an RF card by receiving power from a magnetic field generated from an RFID reader and converting the power into rectified voltage. A reference voltage generator(130) outputs stable reference voltage, which is constant regardless of change of the power voltage. A voltage transformation controller(120) transforms the rectified voltage of the voltage rectifier into the constant voltage based on a comparison result between the power voltage and the reference voltage. The voltage transformation controller includes a first MOS(Metal Oxide Semiconductor) transistor passing the power voltage to the ground depending on an active or inactive state, and a first comparator outputting a current source to control voltage pass amount of the first MOS transistor by comparing the reference voltage with the voltage, which is branched by a resistor array of the power voltage passed to the ground. A first comparer(121) provides stable Vrec voltage by controlling the first MOS transistor promptly even when the Vrec voltage which flows through the first MOS transistor drops or boosted. |
