Smart Key ECU (IPM)

The SMK ECU manages all functions related to "Passive Unlock", "Passive Lock" and "Passive Authorization for Engine Start Operation".

It reads the inputs (Capacitive sensor/Lock button), controls the outputs (e.g. exterior and interior antennas), and communicates via the CAN/LIN (depends on the vehicle) as well as a single line interface to further devices of the car. For communication with the SMART KEY FOB, IPM (SMK ECU) generates a request (challenge) as an encoded and modulated 125 kHz signal at the inductive antenna outputs and receives the SMART KEY FOB's response via the external RF receiver.

The main functional blocks of the IPM are:

• Micro controller with FLASH Memory
• Low speed CAN communication interface
• Single Line Interface to SRX
• Single Line Interface to ESCL
• Single Line Interface to EMS
• Input stage
• LF antenna amplifier/driver

The LF antenna amplifier/driver generates a 125 kHz sinusoidal carrier signal which is distributed to the different antennas.

The LF antenna driver consists of a number of outputs with different switching features, for passive access is used:

• Switch on/off Left side door handle antennae, front and rear
• Switch on/off Right side door handle antennae, front and rear
• Switch on/off bumper antenna for access to the trunk
• Switch on/off interior antenna
• Switch on/off hat shelf antenna
• Switch on/off trunk antenna