Signal name
X4401 Pin #
X4400 Pin #
Joystick_Left
19
Joystick_Up
15
Joystick_Push
17
VLEDOUT2
1
SETCURR2
2
Display and keyboard backlight
The device has one Led Driver (SMPS) that is used to drive both displays and keyboard LEDs. LEDs on display
modules and on keyboard are connected so that there are 4 LEDs on K2 (in series), 3 LEDs on Jordan (in series)
and 4 LEDs on keyboard (in series). These circuits are connected parallel to Led Driver output.
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.
K2 and Jordan backlights can´t be turned on at the same time.
Control signals for LED driver are:
From
To
Voltage
Function
GenOut1
TAHVO
R2302 (10k)
0V / 1.8V
Maximum current
control (0V ->max
curr.)
GenOut2
TAHVO
R2301 (4k7)
0V / 1.8V
PWM
TAHVO
J2309, N2301
PWM 0%-100%,
1.8V
Current PWM
control (16 steps)
GenOut3
TAHVO
V2300
0V / 1.8V
Keyboard LEDs ON
(1.8V) /OFF (0V)
GenIO46
Rap3G
-->
BLS
Display backlight
select (1 = K2
backlights on, 0 =
Jordan backlights
on)
ALS interface
Ambient Light Sensor (ALS) is located in the fold part of the phone. It consists of a lightguide (part of front cover),
components of 1LB PWB: phototransistor (V1000)+ resistor (R1006), NTC + resistors (R1004, R1005, R1007) and
RETU EM ASIC (N2200)on 1HU PWB (Gromit engine). Information of ambient lighting is used to control the
backlights of the phone:
• Keypad lighting is switched on only when environment is dark / dim
• Display backlights are dimmed, when environment is dark / dim
Ambient light sensor itself is a photo transistor which is temperature-compensated by an external NTC resistor.
Retu with its ADC reads the light sensor (LS) and temperature (LST) results.
ALS calibration is not possible in the service points. It is replaced by using selected phototransistors as spare
parts.
RM-42
Nokia Customer Care
System Module
Page 9–24
Company Confidential
9241872 (Issue 1)
Copyright ©2005 Nokia. All Rights Reserved.
