User Guide

Nokia Customer Care Baseband Description and Troubleshooting

2118 (RH-77)

In ACTIVE mode, the mobile terminal is in normal operation, scanning for channels,

listening to a base station, transmitting and processing information. There are several

sub-states in the active mode depending on the mobile terminal present state of the

mobile terminal, such as burst reception, burst transmission, if the DSP is working, etc.

In active mode, SW controls the UEMC RF regulators: VR1A and VR1B can be enabled or

disabled. VSIM can be enabled or disabled and its output voltage can be programmed to

be 1.8 V or 3.3 V. VR2 and VR4—VR7 can be enabled or disabled or forced into low

quiescent current mode. VR3 is always enabled in active mode and disabled during Sleep

mode and cannot be control by SW in the same way as the other regulators. VR3 will

only turn off if both processors request to be in sleep mode.

CHARGING mode can be performed in parallel with any other operating mode. A BSI

resistor inside the battery pack indicates the battery type/size. The resistor value

corresponds to a specific battery capacity. This capacity value is related to the battery

technology.

The battery voltage, temperature, size, and charging current are measured by the UEMC,

and the charging software running in the UPP controls it.

The charging control circuitry (CHACON) inside the UEMC controls the charging current

delivered from the charger to the battery and mobile terminal. The battery voltage rise is

limited by turning the UEMC switch off when the battery voltage has reached 4.2 V. The

charging current is monitored by measuring the voltage drop across a 220 mOhm

resistor.

Power Distribution

In normal operation, the baseband is powered from the mobile terminal‘s battery. The

battery consists of one Lithium-Ion cell capacity of 850 mAh and some safety and

protection circuits to prevent harm to the battery.

The UEMC ASIC controls the power distribution to the whole mobile terminal through

the BB and RF regulators excluding the power amplifier (PA), which has a continuous

power rail directly from the battery. The battery feeds power directly to the following

parts of the system:

•UEMC

•PA

•Vibra

•Display

• Keyboard lights

The heart of the power distribution to the mobile terminal is the power control block

inside the UEMC. It includes all the voltage regulators and feeds the power to the whole

system. The UEMC handles hardware power-up functions so the regulators are not

powered and the power up reset (PURX) is not released if the battery voltage is less than

3 V.