MLX90132 Datasheet, PDF (5/44 Pages) Melexis Microelectronic Systems – 13.56MHz RFID / NFC Transceiver

MLX90132
13.56MHz RFID / NFC Transceiver
RX Reader
The reception stage of the MLX90132 is used in Reader mode to receive information from a transponder or
an NFC/RFID device. This stage performs the analog demodulation using two internal diode detectors on
RX1 and RX2.The information is then filtered with the appropriate bandwidth and finally digitized for further
processing. The receiver inputs RX1 and RX2 are typically connected to the resonance point of the antenna,
through two external attenuation resistors or capacitors to avoid saturation of the internal detector set to
V_RXMAX. The complete receiver stage is automatically configured according to the protocol in use (Protocol
select command (0x02)).
Tag Front-end
This block is enabled in Tag emulation mode and performs all operations related to Tag emulation
functionality with low power consumption. The modulated information coming from an NFC/RFID device is
demodulated through the two built-in detectors connected on RX1 and RX2, filtered with the appropriate
bandwidth and finally digitized for further processing. The full settings of the Tag front-end stage are
automatically set with the selected protocol using the Protocol select command (0x02). The load modulation
used to send back the information in TAG emulation mode is also performed by the Tag front-end block. In
this case, an internal resistor is connected between the two inputs RX1 and RX2, modifying the antenna load.
Digital control & protocol handling
This block is responsible for the control of the device, as well as the frame coding and decoding parts of the
protocols supported by the MLX90132. The MLX90132 exchanges with the application microcontroller, pure
payload information after adding/removing frame related information such as SOF, EOF, EGT … It can also
be configured to calculate the CRC for each communication protocol.
Interface Block
The MLX90132 is addressed through SPI or UART (Reader mode only) interfaces with a specific and simple
set of commands. The built-in 528 byte buffer allows minimum interaction with the application microcontroller.
This reduces the burden of the microcontroller whose resources can be fully dedicated for the application.
Tag/Field Detector
This block manages the enhanced Tag and Field detection capabilities. It generates a detection signal that is
available for the application microcontroller through the interrupt pin IRQ_OUT. It allows the use of the
MLX90132 with low power consumption constraints.
Reference clock and internal oscillator
The built-in reference oscillator works with a reference crystal f_XTAL of 27.12MHz from which the internal
nominal system clock frequency f_HFO of 13.56 MHz is derived. An internal low frequency RC oscillator
frequency f_LFO of 32 kHz is used for low-power operating modes, for example to control the internal timings.
In TAG emulation mode the clock is recovered from the HF field, through the built-in Clock Recovery block. In
case of field loss (e.g. during Reader modulation), an internal backup clock of ~10MHz is used instead.
Power management
The MLX90132 features 2 modes of operation (Active and Idle), subdivided in 6 different states of operation:
 Hibernate, the device typically consumes 1µA
 Sleep, the device typically consumes 20µA
 TAG detection, the device typically consumes 45µA.
 TAG emulation, the device typically consumes 2.5mA.
 Ready (RF field OFF), the device typically consumes 2.5mA.
 Reader, the consumption depends on the antenna load and on the operating conditions
3901090132
Rev. 009
Page 5 of 44
Jan-2014