Panasonic KX-UT248RU / KX-UT248RU-B (serv.man3) Service Manual ▷ View online
13
KX-UT248RU/KX-UT248RU-B
4.2.6.
Key Circuit
The key data is under the matrix control by IC204.
The key information output from LED_STB is input into KEYIN, when the key is pressed.
The key information output from LED_STB is input into KEYIN, when the key is pressed.
The HOOK key is independent from Key Scan Matrix and taken into the port singularly.
KEY Input control timing chart
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.
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.
14
KX-UT248RU/KX-UT248RU-B
4.2.7.
LED Circuit
The lighting of the LEDs is controlled by IC204.
Ringer LEDs are static lighting system.
Other LEDs light up in a dynamic lighting system.
The duty ratio is 1/10 (ON time 1.6ms).
Ringer LEDs are static lighting system.
Other LEDs light up in a dynamic lighting system.
The duty ratio is 1/10 (ON time 1.6ms).
LED dynamic control timing chart
LED lights with 3.3V created by the STB pin of the High output and the COM pin of the Low output.
LED lights with 3.3V created by the STB pin of the High output and the COM pin of the Low output.
15
KX-UT248RU/KX-UT248RU-B
4.2.8.
EHS Circuit
EHS is controlled by IC204.
The audio signals are exchanged with IC503 through HANDSET JACK(JK101).
The audio signals are exchanged with IC503 through HANDSET JACK(JK101).
16
KX-UT248RU/KX-UT248RU-B
4.2.9.
Power Supply Circuit
Block Diagram
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