Power Supply Concept - Siemens SL 10 Service Manual

Private Communication Systems
Mobile Phones

5.3 Power Supply Concept

The SL10 has two main power inputs (see blockdiagram):
1) Battery Voltage (3.6 Volts) connected at the battery contacts
2) Charging Voltage (6.5 Volts) delivered by the desktop charger (using the charging contacts
at the bottom of the phone)
Since the battery voltage is supplying the power supply asic, it is a must to have the battery
(or service adapter) inserted to operate the phone.
You cannot switch on the handset if the battery voltage is not present.
From the 3.6V battery voltage, all other supply voltages of the SL10 are derived, controlled
by the power supply ASIC.
The RF module needs 6.0V for its PA: This voltage is generated by a step-up converter.
The logic module, MMI and IrDA circuit use 2.8V, generated by a linear regulator inside the
ASIC. The operating voltage for the display illumination (100Vpk) is derived from this 2.8V
also.
Furthermore the ASIC generates the supply voltage for the Chip-card and the supply voltage
for the Flash.
Service Manual SL10 V1.1 PN MP ST
R. Fleuren
sm_sl10_lvl2_v11.doc Page 16 of 22 05/98