User Guide

CC Technical Documentation Troubleshooting - Baseband

RM-11

Monitoring the VBAT voltage level is done by the charge control block (CHACON). A

MSTRX='1' output reset signal (internal to the UEM) is given to the UEM's RESET block

when the VBAT>VMSTR+ and UEM enter into the reset sequence.

If VBAT is detected to fall below VMSTR- during start-up charging, charging is cancelled.

It will restart if new rising edge on the VCHAR input is detected (VCHAR rising above

VCH-ET+).

Power Up - RTC Alarm

If phone is in POWER_OFF mode when an RTC alarm occurs, a wake-up procedure begins.

After the baseband is powered ON, an interrupt is given to the MCU. When an RTC alarm

occurs during ACTIVE mode, an interrupt is generated to the MCU.

Power Off

The baseband switches into power off mode if any of following occurs:

• Power key is pressed

• Battery voltage is too low (VBATT < 3.2 V)

• Watchdog timer register expires

The UEM controls the power down procedure.

Power Consumption and Operation Modes

During power off mode, power (VBAT) is supplied to the UEM, BUZZER, VIBRA, LED, PA,

and PA drivers (Tomcat and Hornet). During this mode, the current consumption is

approximately 35 uA, which is the UEM leakage current.

In sleep mode, both processors (MCU and DSP) are in stand-by mode. The phone enters

sleep mode only when both processors make this request. When the SLEEPX signal is

detected low by the UEM, the phone enters SLEEP mode. The VIO and VFLASH1

regulators are put into low quiescent current mode, VCORE enters LDO mode, and the

VANA and VFLASH2 regulators are disabled. All RF regulators are disabled during SLEEP

mode. When the UEM detects a high SLEEPX signal, the phone enters ACTIVE mode and

all functions are activated.

The sleep mode is exited either by the expiration of a sleep clock counter in the UEM or

by some external interrupt (a charger connection, key press, headset connection, etc.).

In sleep mode, the VCTCXO (19.2 MHz Clk) is shut down and the 32 kHz sleep clock

oscillator is used as a reference clock for the baseband.

The average current consumption of the phone can vary depending mainly on the SW

state (e.g., slot cycle 0, 1, or 2) and if the phone is working on IS95 or IS2000 for CDMA.

However, the average consumption is about 6 mA in slot cycle 0 on IS95.