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The UEM has two separate protection limits for over temperature conditions, one for the
charging switch and one for the regulators. The temperature circuitry measures the on-
chip temperature. In case of charging over temperature, the circuit turns the charging
switch off. In case of over temperature in any of the regulators, the UEM powers off.
Description of the Powerstates
Within TFE-4/RV-1 the powerup/powerdown is solved in the following way:
Figure 3: Powerstates of the TFE-4/RV-1 Radio unit
When the car is inactive (ignition is switched off), TFE-4/RV-1 shall be in Standby mode.
In this mode TFE-4/RV-1 is not operating. This mode is characterized by very low power
consumption (less than 1mA). This state will be reached when TFE-4/RV-1 is connected
to the car battery the first time.
In the active mode, the engine-power supply is on and the poweronx line is toggled by
the poweronx generator. Here the phone is generally full active from Power supply point-
of-view. After a short time (determined by Software) the UPP sets the B2BPOWEROFFX
line high and this initiates the transition to Active-Locked mode. In case that the ignition
signal is going to low before that, a direct transition to the sleep mode will happen and
the phone engine will be powered off immediately.
Issue 2.0 Mar/2005
Copyright © 2005 Nokia Corporation.
TF4 Technical Information