Smart Key ECU (SMK ECU)

The SMK ECU manages all functions related to "Passive Unlock", "Passive Lock" and "Passive Authorization for READY mode operation".

It reads the inputs (from Push button in door handle, Start Stop Button (SSB), PARK position Switch), controls the outputs (e.g. from exterior and interior antennas), and communicates via the CAN as well as a single line interface to further devices of the car.

To communicate with the SMART KEY FOB, SMK ECU generates a request (challenge) in an encoded and modulated 125 (or 134.2) kHz signals at the inductive antenna outputs and receives the SMART KEY FOB's response via the external RF receiver.

The main functional blocks of the SMK ECU are:

• Power supply
• Microcontroller with FLASH Memory
• Single Line Interface to EMS
• Input stage
• LF antenna amplifier/driver
• CAN communication with BCM

The LF antenna amplifier/driver generates a 125 (or 134.2) kHz sinusoidal carrier signal which is distributed to different antennas.