Als Interface - Nokia N72 Service Manual

RM-180
System Module
GenOut1
GenOut2
PWM
GenOut3

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.
Issue 1
Table 18 LED driver control signals
From
EM ASIC (N2300)
EM ASIC (N2300)
EM ASIC (N2300)
EM ASIC (N2300)
COMPANY CONFIDENTIAL
Copyright © 2006 Nokia. All rights reserved.
To
R2302 (10k)
R2301 (4k7)
J2309, N2301
V2300
Voltage
0V / 1.8V
0V / 1.8V
PWM 0%-100%,
1.8V
0V / 1.8V
Nokia Customer Care
Function
Maximum current
control (0V ->max
curr.)
Current PWM
control (16 steps)
Keyboard LEDs ON
(1.8V) /OFF (0V)
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