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.

With RFID, chip card NFC has the characteristics of two-way connection and recognition, and work at 13.56 MHz frequency range, about 10 cm distance. NFC technology in ISO 18092, ECMA 340 and ETSI TS 102 102 framework to promote standardization, but also compatible with the wide application of ISO 14443 Type - A, B and get its Felica standard infrastructure of contactless smart CARDS.