User Guide

The master reset threshold controls the internal reset of Retu / (Tahvo). If battery voltage is above VMSTR, UEME’s

charging control logic is alive. Also, RTC is active and supplied from the main battery. Above VMSTR UEME allows

the system to be powered on although this may not succeed due to voltage drops during start up. SW can also

consider battery voltage too low for operation and power down the system.

Power key

The system boots up when power key is pressed (adequate battery voltage, VBAT, present).

Power down can be initiated by pressing the power key again (the system is powered down with the aid of

SW). Power on key is connected to Retu ASIC via PWRONX signal.

Power distribution

Figure 94 Power distribution diagram

Power supply components:

• RETU

• TAHVO

• Helen VCORE SMPS

• BT

• LDO

• camera LDO

• backlight SMPS

All the above are powered by the main battery voltage.

Battery voltage is also used on the RF side for power amplifiers (GSM PA & WCDMA PA) and for RF ASICs Hinku

(Rx) & Vinku(Tx).

RM-1

Nokia Customer Care System Module

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