Description:
> TK4100 is a CMOS integrated circuit for use in 125KHz read only RFID card.
It is compatible with EM format.
Features:
> 64 bit memory array laser programmable
> Several options of data rate and coding available
> On chip resonance capacitor
> On chip voltage limiter
> Full wave rectifier on chip
> Large modulation depth due to a low impedance modulation device
> Operating frequency 100-150 KHz
> Very small chip size convient for implantation
> Very low power consumption
Operation:
Menchester modeulation coding (Type code, data rate is RF/64). Only if the chip produce at both ends of extermal coil induced voltage >=3.5Vpp and the clock rate is 125Khz , it will start working.contactless cards

Contactless IC card smart cards, say again "contactless IC card" or "radio frequency card", is the world's a new technology developed in recent years. Sealing in the card base of its chips, no exposed parts. Not only so, the card is a miniature antenna are embedded in the body, is for the sake of the embedded between the chip and the card reader to communicate with each other, it by the radio waves or electromagnetic induction to exchange information. It has successfully combined radio frequency identification technology and IC technology, solve no source (card without power supply) and contactless these two problems, is a breakthrough in the field of electronics.