Nokia Customer Care TF5 Technical Information
Company Confidential TFE-4/RV-1
Issue 2.0 Mar/2005 Copyright © 2005 Nokia Corporation. Page 8a-17
Company Confidential
Optional the VEBpwr can be shifted to 5.2V by applying 12V(=Vcar) on the Flash-IMEI
input. This is enabled by changing the resistor net R104/R107 with additional R111 to
Ground. By this the feedback path is changed and the voltage is increased to 5.2V. This
higher Voltage is necessary to Flash the IMEI Number into the UEM of the EB.
VIDDU Switch
The VIDDU switch enables the Supply Voltage of the input device and the display unit.
This switch is controlled by the B2BUIpoweron line of the EB. This line has 1.8V level in
active and 0V in inactive state. Additionally this block shall fulfill backwards protection
against Vcarbat and Short-circuit protection against Ground.
Figure 11: VIDDU switch HW-Realization
V119 is responsible for the backwards protection and R134 is responsible for the overcur-
rent protection. The voltage difference is sensed by N104 and V129 will switch off V118
when current is too high.
Power control/Reset Block
This block shall provide the right state of the power supplies depending of the status of
the Vcar, ignition-sense and the power control line B2BPoweroffx, provided by the EB.
Further, it generates the Start-Up pulse on B2BPoweronx line to enable proper starting of
the phone engine.
VEBPWR
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