Nokia RM-57, Руководство по обслуживанию

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From To Voltage Function
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)
ALS interface
Ambient Light Sensor (ALS) is located in the upper part of the phone. It consists of a lightguide (part of front
cover), phototransistor (V4400)+ resistor (R4401), NTC + resistors (R4400, R4402, R4403) and RETU EM ASIC
(N2200). Information of ambient lighting is used to control 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.
Figure 106 ALS HW implementation
Table 19 ALS resistor values
Symbol R1 R2 R3 R4 R5 R6 R7 NTC-res
Value 5 kOhm 15 kOhm 30 kOhm 50 kOhm
470
kOhm
100
kohm
470
kohm 47 kOhm
ASICs
RAP3G ASIC
RAP3G ASIC is a 3G Radio Application Processor. RAM memory is integrated into RAP3G.
In general RAP3G consists of three separate parts:
• Processor subsystem (PSS) that includes the main processor and related functions
• MCU peripherals that are mainly controlled by MCU
• DSP peripherals that are mainly controlled by DSP
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