Smart Key ECU (IBU)

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

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

For communication with the SMART KEY FOB, IBU generates a request (challenge) as an encoded and modulated 125 (or 134.2) 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 IBU are:

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

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