Siemens C45 Repair Documentation page 33

Measurement of Battery and Ambient Temperature
The temperature is measured as a voltage equivalent of the temperature on the
voltage dividers R131,R136,R135 for the ambient temperature by the EGAIM.
The battery temperature is measured directly at (l3) of the EGOLD+. For this,
the integrated Σ∆ converter of the EGAIM of the RX-I base band branch is used.
This Σ∆ converter compares the voltage of
TBAT and TENV internally with a
reference voltage BREF.
Via an analog multiplexer, either the RX-I base band signal, or the TBAT signal
and the TENV signal can be switched to the input of the converter.
The signal MEAS_ON from the EGOLD+ activates the
(GSM TDMA-TIMER G11)
measurement and is used to generate to BREF by the help of R137,R132
Measurement of the Battery Voltage
The measurement of the battery voltage is done in the Q-branch of the EGAIM.
for this BATT+ is connected via a voltage divider R118, R120 to the EGOLD+
(Input limitation 1.33V to 5.91V) .An analog multiplexer does the
(GAIM N2)
switching between the baseband signal processing and the voltage
measurement.
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