User Guide

RM-11

Troubleshooting - Baseband CC Technical Documentation

In the ACTIVE mode, the phone is in normal operation; scanning for channels, listening to

a base station, and transmitting and processing information. There are several sub-states

in the active mode depending on the phone’s present state, such as burst reception, burst

transmission, if DSP is working, etc.

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

disabled. These regulators work of the UEM charge pump. 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, disabled, or forced into low quiescent current mode. VR3 is

always enabled in active mode and disabled during sleep mode and cannot be controlled

by SW in the same way as the other regulators. VR3 will only turn off if both processors

(DSP and MCU) request to be in sleep mode.

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

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

to a specific battery type and capacity. This capacity value is related to the battery

technology.

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

and the EM charging algorithm controls it.

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

delivered from the charger to the battery. The battery voltage rise is limited by turning

the UEM switch off when the battery voltage reaches 4.2 V. The charging current is

monitored by measuring the voltage drop across a 220 mOhm resistor.

Power

In normal operation, the baseband is powered from the phone's battery. The battery

consists of one Lithium-Ion cell. In the case of RM-11, the battery capacity is 780 mAh.

The UEM ASIC controls the power distribution to the whole phone through the BB and RF

regulators excluding the power amplifier (PA) and the DC/DC, which have a continuous

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

parts of the system:

•UEM

•PA

•DC/DC

• Buzzer

•Vibra

• Display and keyboard lights

The UEM is the heart of the power distribution to the phone, which includes all the

voltage regulators. The UEM handles power-up hardware functions so the regulators are

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

than 2.8 V.