• 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.
Figure 57 ALS HW implementation
Table 15 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
E-Mail LED
The device has E-Mail indicator LED.
RM-88
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