User Guide

RM-11

System Module CC Technical Documentation

Sleep Mode

The phone enters Sleep mode when both the MCU and the DSP are in stand-by mode.

Both processors control sleep. When the SLEEPX low signal is detected, the UEM enters

Sleep mode. In this mode, the VCORE, VIO and VFLASH1 regulators are put into low

quiescent current mode. All RF regulators — with the exception of VR2 and VR3 — are

disabled in sleep mode. When the SLEEPX is set high and is detected by the UEM, the

phone enters Active mode and all functions are activated. Sleep mode is exited either by

the expiration of a sleep clock counter in the UEM, or by some external interrupt gener-

ated by a charger connection, key press, headset connection, etc. While in Sleep mode,

the main oscillator is shut down and the baseband section uses the 32 kHz sleep clock

oscillator as its reference.

Charging Mode

Charging can be performed in parallel with any other operating mode. The Battery Size

Indicator (BSI) resistor inside the battery pack indicates the battery type/size. The resistor

value corresponds to a specific battery capacity and technology. Under UPP software

control, the UEM's AD converters measure the battery voltage, temperature, size, and

current. 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 has reached VBATLim

(programmable charging cut-off limits are 3.6V, 5.0V, 5.25V). Measuring the voltage

drop across a 0.22 Ohm resistor monitors the charging current.