MOBILE COMMUNICATIONS DIVISION
CUSTOMER SERVICES
Version 1.0 22/11/2006
Created by Konrad Szombara
Page 76 of 103
TCXO Regulator (VTCXO): 2.8 V
The TCXO regulator is intended as a supply for a temperature compensated
crystal oscillator, which needs power supply with ultra-low noise. VTCXO is rated
to 20 mA output current and is turned on when TCXOEN is asserted.
RTC Regulator (VRTC): 1.8 V
The RTC regulator is used to charge the RTC backup battery needed by real-time
clock module. It also provide the power source directly to the RTC module. In
addition, it features a very low quiescent current since this regulator is running all
the time, even when the handset is switched off. It also has reverse current
protection with very low leakage current. When the main battery is removed, the
backup battery can supply RTC module when RTC regulator is unavailable.
Microphone Regulator (VMIC): 2.5 V
The Microphone regulator generates 2.5V power needed by microphone. It is
rated for 1 mA of supply current. This regulator is optimized for extremely high
rejection to power source noise around 217Hz frequency, which is easily
generated by RF power amplifier.
SIM Regulator (VSIM): 2.8 V
The SIM regulator generates the voltage needed by 1.8V or 3V SIM card. It is
rated to 20 mA of supply current and can be controlled independently from the
other regulators.
Applying a low to SIMEN shuts down the SIM regulator. A discharge circuit is
active when SIMEN is low. This pulls the SIM regulator output to low state when
the regulator is disabled. SIMVSEL allows the SIM regulator to be programmed
for either 1.8 V or 2.8V. Asserting a high on SIMVSEL sets the output to 2.8 V.
SIMEN and SIMVSEL allow the baseband processor to properly sequence the
SIM supply when determining which type of SIM card is inserted.
Peripheral Regulator(VEXT) : 2.8V
The external Interface regulator supplies the Radio digital interface and the high
voltage (>1.8V) interface between the digital baseband processor and various
peripherals, such as the LED indicators and the LCD display.
In this model, VEXT also supplies the power of AIT811 external interface, CMOS
module external interface and LCD module. Power loading of VMEM is highly
reduced by using VEXT instead, preventing the power instable of VMEM when
it's load is high.
