Power Supply Concept - Siemens S11 Service Manual

4.3Power Supply Concept

The S11 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
a) The plug-in charger at the charging plug
b) The desktop charger using the charging contacts at the bottom of the phone
c) The car kit using the charging connection at the bottom of teh phone
Since the battery voltage is supplying the power supply asic, it is always needed to
operate the phone. You cannot switch on the handset if the battery voltage is not
present.
Blockdiagram S11 Power Supply
VCC_DD
0.25 A
+3.6 V
Batt+
+6.5 V
Power
1A
Ignition
Watchdog
ON_OFF Button
From the 3.6 V battery voltage, all other supply voltages of the S11 are derived,
controlled by the power supply ASIC.
The VCC_DD voltage is used to supply external accessories through the bottom
connector.
The RF module needs 6.0 V for its PA, this voltage is generated by a step-up
converter.
The logic module uses 2.8 V, generated by a simple linear regulator.
V1.1
VDD
Control
Charging
Control
Control
S11
Power Supply
ASIC
Power Detection Charging On
(to µP) (from µP)
12
Private Communication Systems
Mobile Phones
Switching
Regulator
Linear
Regulator
+6.0 V
RF Supply
+2.8 V
Logic Supply
SIM Supply
RESET
PN MP ST
D. Schnoor
04/98