Proximity Cards

Proximity card are contactless integrated circuit devices used for security access or payment systems.

  • 125 kHz devices or the newer 13.56 MHz contactless RFID cards
  • also known as contactless smartcards
  • have a range of 0-3 inches in most instances, allowing the user to leave the card in one’s wallet, or purse

How do smart cards work ?

Proximity cards use an LC circuit. An IC, capacitor, and coil are connected in parallel. The card reader presents a field that excites the coil and charges the capacitor, which in turn energizes and powers the IC. The IC then transmits the card number via the coil to the card reader. The card readers communicate in Wiegand protocol that consists of a data 0 and a data 1 circuit.


  • identification cards
  • keycards
  • payment cards
  • public transit fare cards

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