Motorola D10 Service Manual page 70

BenQ
3.9 LED circuit
U7
UMH10N
BGND
PWL
BL
From U1/ULYSEE
Description
56f16 employs three LEDs for LCD module backlight and eight LEDs
for keypad backlight. To light up the LEDs, Ulysse applies PWL (Pulse
Width Light) at BL to drive LEDs. U7 is used as an inverter to enable
BQ2. Under the default condition (VBAT=3.6V), the average current of
one LCD backlight LED is about 12mA and of one keypad backlight
LED is about 7.5mA. In 56f16, all the LEDs are yellow-green color
and forward voltage is 1.9V
VBATBB
R34
2
2K
R39
R40
39 39
D3 D4
22-21 22-21
BGND
29
D18
RB520S-30
1
BQ2
3
BC807-40W
R35
22 (0805)
D7
D5 D6
19-21 19-21 19-21
Rev 1.0
D8
D9 D10
19-21 19-21 19-21
BGND