ID card EM4205 EM4305 smart card 125KHZ,134KHZ 
 
EM4205/4305 is a CMOS integrated circuit intended for use in electronic Read/Write RF transponders. It is
suitable for low cost solutions like animal tagging applications. The IC communication protocol is compatible with the EM4469/4569 family.
The main difference between the EM4205 and EM4305
is that:
EM4305 are bumped with enlarged pads for the twocoil inputs. The enlarged bumped pads of the EM4305 transponder are intended for direct antenna connection avoiding the need of a module.
EM4305 offers a 330pF resonant capacitor version The IC is powered by picking up energy from a continuous 125 kHz magnetic field via an external coil, which together with the integrated capacitor form a
resonant circuit. The IC reads out data from its internal EEPROM and sends it out by switching on and off a
resistive load in parallel to the coil using a large modulation index. Commands and EEPROM data updates can be executed by 100% AM modulation of the 125 kHz magnetic field.
The EM4205/4305 supports bi-phase and Manchester data encodings.
The EM4205/4305 operating modes are stored in the EEPROM configuration word. All EEPROM words can be write-protected by setting protection bits.
The IC contains a factory programmed 32 bit unique identifier number (UID).
     EM4205: 2 resonant capacitor versions 210pF or 250pF selectable by mask option. The resonant capacitor can be trimmed, at factory level, to offer accuracy on the tolerance of 3%.