User Guide

PAMS
Technical Documentation
NSE–8/9
System Module
Page 2– 70
Issue 1 07/99
Table 35. Input and output characteristics of the UISwitch IC (continued)
UnitMaxTypMinSymbolPinParameter
Buzzer FET switch Rdson BUZZER 1 
VIBRA nominal current
@ VBAT = 3.6V
Rvibra (typ.) = 10
VIBRA Ivibra 120 mA
VIBRA FET switch Rdson VIBRA 1 
For a complete specification of the UISwitch IC.
Backlight
4 LEDs are used for LCD back lighting. They are controlled by the signal
LCD_light coming from the Cobba_GJP. When LCD_light is HIGH, lights
are ON and when LCD_light is LOW, lights are OFF. Default state for
LCDLED_CNT pin is LOW (internal pull–down resistor).
The UISWITCH has an adjustable constant current sink for the pin
LCD_LED. The current can be adjusted by means of an external resistor
connected to adjustment pin LCDLED_ADJ. The typical LCD backlight
current is 50 mA with R415 of 12k. LCD backlight current can be
reduced linearly by increasing the value of adjustment resistor in
LCDLED_ADJ line.
6 LEDs are used for keyboard back light. They are controlled by the
signal Key_light from Cobba_GJP. When Key_light is HIGH, lights are ON
and when Key_light is LOW, lights are OFF. Default state for UIswitch
KBDLED_CNT pin is LOW (internal pull–down resistor).
The UISWITCH has an adjustable constant current sink for the pin
KBD_LED. The current can be adjusted by means of an external resistor
connected to adjustment pin KBDLED_ADJ. The typical keyboard
backlight current is 60 mA with R418 of 10 k. Keyboard backlight
current can be reduced linearly by increasing the value of adjustment
resistor in KBDLED_ADJ line.
Buzzer
A buzzer is used for giving alerting tones and/or melodies as a signal of
an incoming call. The buzzer is controlled with a PWM output signal,
BUZZER from the MAD2PR1. A dynamic type of buzzer is used since the
supply voltage available can not produce the required sound pressure for
a piezo type buzzer. The alert volume can be adjusted either by changing
the pulse width causing the level to change or by changing the frequency
to utilize the resonance frequency range of the buzzer.
Each time the buzzer is activated the sw commands the DC/DC converter
output to max level to have the highest voltage swing available for the
buzzer.