MLX90132 Datasheet, PDF (37/44 Pages) Melexis Microelectronic Systems – 13.56MHz RFID / NFC Transceiver

MLX90132
13.56MHz RFID / NFC Transceiver
11 Application Information
11.1 External Antenna network
RF communication performance depends on the external system antenna network and resonance conditions.
The antenna matching of the MLX90132 is reduced to a minimal component count, composed of two serial
capacitors Cs and one parallel capacitor Cp. A parallel resistor Rp can also be added to adjust the antenna
damping thus reducing detuning effect provoked by the presence of TAGs or Readers in front of the
MLX90132. Two serial resistors R_RX have to be adjusted in order to avoid entering the clamping region (see
Table 36 below). Finally, depending on EMC constraints, an EMI filter can be added to reduce the emission
of harmonics generated by the square wave at the outputs TX1 and TX2.
Figure below gives an example of the external matching network to connect the antenna. For more
information, please refer to the application note AN1_MLX90130_32_AntennaDesignGuidelines available on
the Melexis website.
RX1
TX1
MLX90132
TX2
RX2
RRX
LEMI
CEMI
LEMI ^CEMI
RRX
CS
CP
RP
CS
Figure 14: External antenna matching network example
11.2 Application schematic
VDD
Antenna
27.12MHz
Matching
Example of
EMI Filter
VDD
GND_DIG
XIN
XOUT
GND_TX
VDD_TX
TX1
TX2
NC
MLX90132
VDD
IRQIN
VDC
RX1
RX2
GND_RX
NC
NC
Application
Microcontroller
Figure 15: MLX90132 application schematic in SPI mode
3901090132
Rev. 009
Page 37 of 44
Jan-2014