Nokia 6610i Service Manual
CCS Technical Documentation
7-System Module and User Interface
Company confidential
RM-37
Issue 1 04/2004
©Nokia Corporation.
Page 57
LCD & Keypad Illumination
In RM-37 white leds are used for LCD and keypad illumination. For LCD illumination two
leds are used and for keypad six leds.
leds are used and for keypad six leds.
Figure 27:
Current through leds is controlled by transistor circuitry. External transis tor driver cir-
cuitry is used as constant current source in order to prevent any change in battery volt-
age be seen as changing led brightness.
cuitry is used as constant current source in order to prevent any change in battery volt-
age be seen as changing led brightness.
LEDs are controlled by the UEM PWM outputs. Both LEDs are controlled by KLight output
of the UEM. Current flow through the LEDS is set by biasing the transistor and limiting
the current by resistors.
the current by resistors.
Internal Speaker
The internal earpiece is a dynamic earpiece with an impedance of 32 ohms. The earpiece
is low impedance one since the sound pressure is to be generated using current and not
voltage as the supply voltage is re stricted to 2.7V. The earpiece is driven directly by the
UEM and the ear piece driver in UEM is a bridge amplifier.
is low impedance one since the sound pressure is to be generated using current and not
voltage as the supply voltage is re stricted to 2.7V. The earpiece is driven directly by the
UEM and the ear piece driver in UEM is a bridge amplifier.
Buzzer
Buzzer is used to generate alerting tones and melodies to indicate incom ing call. It is
also used to generate keypress and warning tones for the user. Buzzer is controlled by
PWM (Pulse Width Modulation) signal generated by the buzzer driver of the UEM. Target
SPL is 100dB (A) at 5cm.
also used to generate keypress and warning tones for the user. Buzzer is controlled by
PWM (Pulse Width Modulation) signal generated by the buzzer driver of the UEM. Target
SPL is 100dB (A) at 5cm.
Vibra
A vibra alerting device is used to generate a vibration signal for an incoming call. Vibra is
located in the bottom end of the phone and connection is done with spring contacts.
Vibra interface is the same like other DCT4 projects. The vibra is controlled by a PWM
signal from the UEM. Frequency can be set to 64, 129, 258 or 520 Hz and duty cycle can
vary between 3% - 97%.
located in the bottom end of the phone and connection is done with spring contacts.
Vibra interface is the same like other DCT4 projects. The vibra is controlled by a PWM
signal from the UEM. Frequency can be set to 64, 129, 258 or 520 Hz and duty cycle can
vary between 3% - 97%.
Cin
Cout
DLIGHT
VBAT
LCD Illumination
Keyboard Illumination
Cosc
Coil
Schottky
R
Rlcd
Vovp
Ext
Is
En
Cx
Gnd
FB
LED Driver
V in