User Guide

CC Technical Documentation Troubleshooting - Baseband
RM-11
Issue 1 02/2004 ©2004 Nokia Corporation Confidential Page 23
Display and Keyboard
The RM-11 uses LEDs for LCD and keypad illumination. There are three LEDs for the LCD
and eight LEDs for the keypad. The KLIGHT signal is used to drive the LED driver for the
LCD and keyboard.
The RM-11 also uses a color LCD. The interface utilizes a 9-bit data transfer and is similar
to the DCT3-type interface, except the Command/Data information is transferred
together with the data.
Figure 18: D/C bit set during each transmitted byte
Flashlight
The flashlight feature on C-Rio is driven by the White LED Driver and controlled by the
UEM. The circuit for the flashlight is driven by TK11851TL. In this situation, the driver is
used as a boost DC/DC. Vout is set using three precision resistors in R300, R316, and 317.
Vout = Vfb * (1+ (R316+R317)/ R300). The TK11851L is an active-high enable device,
whose enable signal is tied to Klight/Dlight signals from the UEM. When Klight goes high
it turns on the TK11851TL driver and the V301 transistor, which allows a path to GND.