LG G1610, Service Manual

Page: 30 / 126

3. TECHNICAL BRIEF
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3.10 Keypad Switches and Key Backlight Illumination
(1) Keypad Switches
The key switches are metal domes, which make contact between two concentric pads on
the keypad layer of the PCB when pressed. There are 21 switches (KB500-KB522),
connected in a matrix of 5 rows by 5 columns, as shown in Figure, except for the power
switch (KB500), which is connected independently. Functions, the row and column lines of
the keypad are connected to ports of AD6525. The columns are outputs, while the rows are
inputs and have pull-up resistors built in. When a key is pressed, the corresponding row and
column are connected together, causing the row input to go low and generate an interrupt.
The columns/rows are then scanned by AD6525 to identify the pressed key.
Figure 3-15 Circuit Diagram of Keypad Switches
KB502
$V
$V $V $V $V
$V $V $V $V
$V
$V $V
$V
$V
$V $V $V
1
KB500
$V
$V
END
KB503
$V
2
KB504
$V
3
KB501
$V
CLR
KB505
$V
LEFT
KB506
$V
MENU
KB507
$V
4
KB508
$V
5
KB509
$V
6
KB510
$V
UP
KB511
$V
SELECT
KB512
$V
7
KB513
$V
8
KB514
$V
9
KB515
$V
RIGHT
KB516
$V
SEND
KB517
$V
*
KB518
$V
0
KB519
$V
#
KB520
$V
DOWN
CONFIRM
KB521
$V
680
R507
$V
680
R506
$V
$V
680
R508
$V
680
R509
$V
680
R510
$V
$V
SP507
SP500
SP508 SP509 SP510 SP51
1
SP501
SP508 SP509 SP510
SP51
1
SP508 SP509 SP510 SP51
1
$V
SP512
$V
SP517
$V
SP526
SP522 SP524 SP523 SP525
R511
680
$V
R512 680
$V
R513 680
$V
R514
680
$V
R515 680
POWERKEY
KEYROW0
KEYROW1
KEYROW2
KEYROW3
KEYROW4
KEYCOL0
KEYCOL1
KEYCOL2
KEYCOL3
KEYCOL4