MLX74190 – Two-fold high power LF initiator with Immobilizer

The MLX74190 is a Low-frequency (LF) initiator composed of two high power LF drivers and built-in immobilizers (IMMO).

The main application for the MLX74190 is Automotive Passive Start, where the IC transmits a high power LF telegram to wake-up the key inside the car.

The MLX74190 also features two built-in Immobilizers (for ASK and FSK communications), used when the battery of the key is depleted. In this case, the key is placed in a specific zone close to the initiator and a full passive RFID communication is initiated. The load modulation signal returns by the key is received and demodulated by the MLX74190.

The MLX74190 can also serve for a similar purpose with other vehicles such as; motorcycles, scooters, all-terrain vehicle (ATV), jet skis, snowmobiles and motorboats, where the key holder can be detected when approaching the engine and will be able to activate it from a “Start” button, or as a ‘dead man switch’ so that if the driver falls off then the engine is automatically cut. In addition it may be incorporated into building access systems, tire pressure monitoring system (TPMS) initiators and pet identification system.

Both LF drivers are independently programmable to generate sine (max. 1Ap) or square (max. 2.5Ap) waves, with a frequency from 109kHz to 140kHz and an output amplitude from 0.25 to 32Vpp. The two drivers can be used in full or half bridge configuration and are protected against overload (over-current and over-temperature). A built-in diagnosis function allows detecting any wrong connection with the LF antenna (Short to GND, Short to Vbat, open load or wrong resonance frequency).

The MLX74190 is supplied by an external VS voltage from 6-40V and VDD voltage of typically 5V. The VS voltage can be generated by an external DC-DC converter or by DC voltage from vehicle supply.

The MLX74190 is controlled through a standard SPI interface (SDI, SDO, SCK and NCS) and an interrupt pin is generated on-purpose by the IC. The MLX74190 is clocked either with a 2 MHz clock frequency signal coming from the MCU or by an on-chip oscillator connected to an external 4 MHz crystal or ceramic resonator.

FEATURES

High power drivers (2.5Ap in square mode)
Output power programmable from 0.25 to 32Vpp
Output frequency programmable from 109kHz to 140kHz
Full or Half bridge capabilities
Antenna fault detection
Protected power outputs (over current and T°)
Built-in ASK/FSK immobilizers
SPI port for easy control

APPLICATIONS

Passive Start system
TPMS Initiator
LF door opener
Active RFID initiator

Find here the MLX74190 Technical Forum E-Mail Contact