Private Communication Systems
Power Supply Concept
The C25 has two main power inputs:
1) Battery Voltage (3.6 Volts) connected at the battery contacts
2) Charging Voltage (6.5 Volts) delivered by the different charger types (see
accessory list) via the Lumberg connector at the bottom of the telephone.
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
From the battery voltage all other supply voltages of the C25 are derived, controlled
by the power supply ASIC.
The RF power amplifier needs an operation voltage of 5,4Volts, which is generated
by a DC-DC step-up converter.
The logic module uses 2.9 V, generated by a regulator inside the ASIC.
Service Manual C25 / C2588
ICP CD ST
Page 19 of 32