Power - Nokia RH-27 Series Technical Documentation Manual

RH-27
Troubleshooting - Baseband
In the ACTIVE mode, the phone 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 phone 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 dis-
abled and its output voltage can be programmed to be 1.8V or 3.3V. 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 (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 tech-
nology.
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 has reached 4.2 V. 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 con-
sists of one Lithium-Ion cell. In the case of Lancelot, the battery capacity is 850 mAh.
The UEM ASIC controls the power distribution to 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 following parts
of the system: UEM, PA, DC/DC, buzzer, Vibra, display- and keyboard lights.
The heart of the power distribution to the phone is the power control ASIC, called UEM.
It includes all the voltage regulators and feeds power to the whole system. UEM handles
hardware functions of power up so that regulators are not powered and power up reset
(PURX) is not released if the battery voltage is less than 2.8 V.
RH-27 Baseband is powered from five different UEM regulators: VANA, VIO, VFLASH1,
VFLASH2, and VCORE DC/DC. See Table 1.
UEM voltage regulators: VR1A, VR1B, VR2, VR3, VR4, VR5, VR6, and VR7 are used by RF.
See Table 2.
Page 10
©2003 Nokia Corporation
CCS Technical Documentation
Confidential Issue 1 11/2003