Internal Power Management

Internal Power Management (Sleep Mode)

Because the LM's operating current consumption would place unwanted load on the vehicle battery during long periods of parking and when its functions are not needed, it is provided with mechanisms for identifying out-of-service periods and reducing the power requirement while retaining wake-up readiness.

The micro-processor of the LM functions with nominal operating current when:

- The CAN is active.
- Terminal R (input) is active.
- Terminal 15 (input) is active.
- Lamp functions are active.
- Anti-theft alarm-system alarm is active.
- The follow-me-home light circuit is active.

If none of the above conditions apply, the LM transmits it's sleep readiness and then switches into sleep mode. It also switches into this mode when the sleep conditions are in place and the sleep acknowledge bit has been received from another bus user.

After approx.30 s the current consumption drops from approx.120 mA to below 1 mA. The LM awakens cyclically and input signals are monitored so that the system can respond to possible changes in the switch states and the external inputs.

A CAN telegram received during this power-saving mode results in system wake-up. Following a wake-up period of max.100 ms, the LM is again ready for communication, relevant telegrams are fully received and evaluated in each case so that no bus information is lost.

If no wake-up condition occurs for a period exceeding 390 s, the switch inputs are no longer monitored and the zero-signal current is reduced further.

System wake-up is possible by CAN telegrams, an activated terminal 15 or the hazard warning button.

Redundant Data Storage

The LM shares responsibility with the CAS for the storage of the Vehicle Identification Number and the FA (Vehicle Order).