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• BT LDO

• camera LDO

• MicroSD LDO

• camera SMPS

• 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) and for RF ASIC Ahne.

Discrete power supplies are used to generate 1.8V and 2.8V for the camera module, 2.85V for MicroSD card

and max. 18V for backlight LEDs.

The device supports both 1.8V/3V SIM cards which are powered by EM ASIC (N2200) / VSIM1. EM ASIC (N2200)

s VSIM2 is not used. USB accessories which needs power from the device are powered by EM ASIC (N2300) /

VOUT.

Because LED driver in EM ASIC (N2300) is not used, the external SMPS is used instead. External LED SMPS is still

controlled by EM ASIC (N2300) and powered by battery voltage.

System power-up

After inserting the main battery, regulators started by HW are enabled. SW checks, if there is some reason to

keep the power on. If not, the system is set to power off state by watchdog. Power up can be caused by the

following reasons:

• Power key is pressed

• Charger is connected

• RTC alarm occurs

• MBUS wake-up

After that:

• EM ASIC (N2200) activates sleep clock and VANA, VDRAM, VIO and VR1 regulators.

• Voltage appearing at EM ASIC (N2200)’s RSTX pin is used for enabling EM ASIC (N2300) ASIC.

• EM ASIC (N2300) enables VCORE regulator and its internal RC-oscillator (600kHz).

• VCTCXO regulator is set ON and RF clock (main system clock) is started to produce.

• EM ASIC (N2200) will release PURX ~ 16ms after power up is enabled (the RF clock is then stable enough).

• Synchronizing clock (2.4MHz) for EM ASIC (N2300) is started to be produced. After PURX is released and two

rising edges of 2.4MHz synchronous clock have been detected in SMPSClk input EM ASIC (N2300) is starting

to use that instead of 600kHz internal RC-oscillator.

• HW start-up procedure has been finalized and the system is up and running. Now it is possible for SW to

switch ON other needed regulators.

Clocking scheme

In BB5.0, two main clocks are provided to the system: 38.4MHz RF clock produced by VCTCXO in RF section

and 32.768kHz sleep clock produced by EM ASIC (N2200) with an external crystal.

RF clock is used by RAP that then provides (divided) 19.2MHz SysClk further to the application processor. RAP

has internal PLLs which then create clock signals for other peripheral devices/interfaces like SD card, SIM, CCP,

I2C and memories.

32k Sleep Clock is always powered on after startup. Sleep clock is used by RAP.

SMPS Clk is 2.4MHz clock line from RAP to EM ASIC (N2300) used for switch mode regulator synchronizing in

active mode.

RM-170; RM-171

System Module Nokia Customer Care

Issue 1 COMPANY CONFIDENTIAL Page 9 –11