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, NFC id card 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.
NFC chip is installed on a mobile phone, mobile phone can realize small electronic payment and read other NFC devices or label information. NFC short interaction greatly simplify the whole certification identification process, make to visit each other between the electronic equipment is more direct, more safety and more clearly. Through the NFC, computers, digital cameras, mobile phones, pdas, and other equipment can be very convenient for the wireless connection between achieving data exchange and service.
NFC is now NFC CARD used in phones, Nokia 6131 I have demonstrated the NFC technology of bus IC card phone. Not only can bus card, also can be in certain convenience store for micropayments.