Panasonic KX-NT553RU-B / KX-NT556RU-B Service Manual ▷ View online
13
KX-NT553RU/KX-NT553RU-B/KX-NT556RU/KX-NT556RU-B
KEY Input control timing chart
KEYIN pins have a internal pull-down resistor.
KEYIN pins have a internal pull-down resistor.
If KEY is pushed, high level is latched by connecting STB(output high) and KEYIN. If not, low level is latched.
The value is fixed by reading twice.
The value is fixed by reading twice.
14
KX-NT553RU/KX-NT553RU-B/KX-NT556RU/KX-NT556RU-B
4.2.7.
LED Circuit
The lighting of the LEDs is controlled by IC205.
Ringer LEDs are static lighting system.
Other LEDs light up in a dynamic lighting system.
Ringer LEDs are static lighting system.
Other LEDs light up in a dynamic lighting system.
LED dynamic control timing chart
LED lights with 3.3V created by the STB pin of the High output and Transistor Collector pin of the Low output.
LED lights with 3.3V created by the STB pin of the High output and Transistor Collector pin of the Low output.
15
KX-NT553RU/KX-NT553RU-B/KX-NT556RU/KX-NT556RU-B
4.2.8.
EHS Circuit
EHS is controlled by IC205 (Plantronics only).
Jabra EHS is controlled by IC502 (BBIC).
The audio signals are exchanged with IC502 through HANDSET JACK(JK102).
Jabra EHS is controlled by IC502 (BBIC).
The audio signals are exchanged with IC502 through HANDSET JACK(JK102).
16
KX-NT553RU/KX-NT553RU-B/KX-NT556RU/KX-NT556RU-B
4.2.9.
Power Supply Circuit
Po
E_
G
Po
E_
AG
+
9
V
o
r 12V
L2
S
W
DV
F
Pa
n
e
ll
M
a
in
L
C
D
S
e
lf
La
be
ri
ng LC
D
DS
S
+1
.0
V
+1
.8
V
+5
V
AG
+
5
V_
fr
o
m
PC
RJ
4
5
(L
A
N
)
Po
E
DCDC
12V
9V
+3
.3
V
US
B
DDR2
3.
3V
A
+
-
DCDC/
D
ig
it
a
l
AMP
Analog
H
a
nds
et
MI
C
S
peak
er
RJ
4
5
(P
C
)
DG
AC
9V
/750m
A
45
V
C
P
U
/
KEY /
L
E
D
1.
8V
1.
2V
DCDC
5V
DCDC
1.
8V
DCDC
1.
0V
DDR
I
F
DCDC
3.
3V
DV
DDI
O
D
V
D
D
L
Digital Part
P
LLV
D
D
L
AVD
D
H
AVD
D
L
NA
ND F
L
A
S
F
B
a
c
klig
h
t
L
CD(
M
a
in
)
L
C
D
(Self)
B
a
c
klig
h
t
H
e
ads
et
EHS
KEY /
L
E
D
ASI
C
Analog Part
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