User Guide

Pin Signal I/O Engine connection Notes

3 Flip clock <-> Application

processor

sda I2C clock

GND GND Flip ground

Display and keyboard backlight

The device has one LED Driver (SMPS) that is used to drive display and SW keys.

Both display LEDs (4pcs) and keyboard LEDs (2pcs) are connected in series.

Current adjustment of the driver is done from the display LED branch, and keyboard current also depends on

the display brightness.

In a typical use case, keyboard LEDs are turned ON only in dark ambient lighting conditions.

ALS interface

Ambient Light Sensor (ALS) is located in the upper part of the phone. It consists of the following components:

• lightguide (part of the front cover)

• phototransistor (V4400) + resistor (R4401)

• NTC + resistors (R4400, R4402, R4403)

• EM ASIC (N2200)

Information on ambient lighting is used to control the backlights of the phone:

• Keypad lighting is switched on only when the environment is dark / dim

• Display backlights are dimmed, when the environment is dark / dim

The ambient light sensor itself is a photo transistor, which is temperature-compensated by an external NTC

resistor. N2200 reads the light sensor (LS) and temperature (LST) results.

ALS calibration is not possible in the service points. ALS is serviced by replacing faulty phototransistors.

RM-10;RM-24

Nokia Customer Care System Module

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