Itut Keyboard And Side Key Illumination - Nokia n81 Service Manual

RM-179; RM-223
System Module and User Interface
Figure 69 Illumination overivew

ITUT keyboard and side key illumination

ITUT keyboard is illuminated with 2x2 LEDs in parallel and side keys are illuminated with 1x2 LEDs in parallel.
Each two LEDs are driven by a High-Side driver output (N2302) with 10mA which results in 5mA per LED. ITUT-
LEDs are connected to channel A and side-LEDs are connected to channel B. Each channel can be separately
switched on and off (ENA, ENB). Both channels are ORed (D2400) with PWM signal to achieve dimming when
display is dimmed.
Issue 1 COMPANY CONFIDENTIAL Page 6 –29
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