Proximity Integrated Circuit Card (PICC) is a generic term for contactless smart cards such as the RFID card that are used in close proximity (proximity) to a card reader for payment purposes. The distance is about 15 cm.
The PICC card is a passive smart card that draws its energy via inductive coupling from the proximity coupling device( PCD), which is the RFID reader. Such PICC cards, like most passive RFID tags, operate at 13.56 MHz. Proximity cards are standardized under ISO 14443, they operate with chips and LC circuits and have no power supply of their own. This is provided by charging the capacity of the LC circuit via the RF coupling between the reader and the PICC card. For this purpose, LC circuits tuned to a common frequency are located in the reader and on the PICC card. The energy stored in the capacitance powers the chip and can activate the desired information.
The data transmission between the card reader and the PICC card uses the Wiegand protocol. The information is generated by capacitive or resistive loading of the LC circuit. This leads to a change in the absorption behavior, which is detected by the reader.