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.

Chip-based proximity card cards: "The chip is embedded on the card and contains information in a encrypted format". In addition, it includes a personal identification number (PIN)." This technology needs to adhere to EMV standards - Europay, MasterCard and Visa.