Modes Of Operation; Power Distribution - Nokia RM-761 Service Manual

RM-761; RM-799; RM-800
System Module

Modes of operation

Figure 2 also shows the sleep mode transitions in a PMU context. When the system enters sleep mode, the
state of a number of the power management functions will be changed controlled by the RF_SYSCLK_EN signal
to reduce current consumption. Most devices can be put into off or standby mode such as the LDOs and DC/
DC converter, to minimize quiescent current. The DC/DC converter can be programmable into its low power
mode (PFM) and VCORE changes the output voltage to a lower value. The HPBG (HIGH PRECISION BANDGAB) is
deactivated and the DCXO in RF is switched off.
Exit from sleep mode is initiated by expiration of the sleep timer or detection of a HW interrupt.

Power distribution

The X-GOLD213 contains regulators for all power supplies needed in various parts of the chip. The regulators
are LDO type linear regulators except the 1.8V step down DCDC converter. The LDO's are powered from either
battery or the step down converter. The following figure depicts the complete power management unit with
the regulators. Supply inputs VRF1 and VDD1V8 are connected to the output of the step down converter SD1,
thus increasing the efficiency of the downstream supplies for the RF, the digital core and the analog part by
the conversion factor of the step down. The remaining regulators are supplied directly from the battery
voltage.
Figure 51 X-GOLD213 power management unit
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