DOWNLOAD Panasonic KX-DT321UA Service Manual ↓ Size: 1.32 MB | Pages: 43 in PDF or view online for FREE

Model
KX-DT321UA
Pages
43
Size
1.32 MB
Type
PDF
Document
Service Manual
Brand
Device
PBX / DIGITAL PROPRIETARY TELEPHONE
File
kx-dt321ua.pdf
Date

Panasonic KX-DT321UA Service Manual ▷ View online

5
KX-DT321UA/KX-DT321UA-B
4 Technical Descriptions
4.1.
Block Diagram
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KX-DT321
UA
/KX-DT321
UA
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6
KX-DT321UA/KX-DT321UA-B
4.2.
Circuit Operations
4.2.1.
Key Input Control Curcuit
The key data is under the matrix control by 20 to 23(KEYOUT) and 28 to 35(KEYIN) of IC6.
The key information output from KEYOUT is input into KEYIN, when the key is pressed.
7
KX-DT321UA/KX-DT321UA-B
4.2.2.
LCD Control Circuit
KX-DT321 uses a 16 characters by 1 line LCD.
Power is supplied to LCD from +5V rail, formed as follows:
Pin 24 of IC6 is made to switch, forming a square waveform which is input to IC8 pin 2. The output of IC8 pin 4 switches between
+3.3V and 0V. When the output is low, C603 charges via D61. When output is high, anode of D62 rises to 6V and C601 is charged
via D62. D63 limits the voltage across C601 to +5V. D5V powers the LCD and also IC10.
IC10 is a converter circuit to allow the 3V output of IC6 to drive the LCD, which uses 5V inputs.
LCD contrast is adjusted by means of voltage level supplied at pin 3 of LCD module.
It is adjusted to one of 3 settings by means of a bias circuit (R600, R622) and IC6 pins 19 and 59, according to the following table:
Data is sent to the LCD module via IC10 from the processor using a 3-wire interface (IC6 pins 13, 14, 15).
Contrast
IC6 pin 59
IC6 pin 19
High
L
L
Middle Z
L
Low
Z
L
8
KX-DT321UA/KX-DT321UA-B
4.2.3.
LED Circuit
The lighting of the LEDS is controlled by pin 14 to 18 (Row) and pin 8 to 13 (Colum) of IC2.
The LED lights up in a dynamic lighting system.
The duty ratio is 1/8 (ON time 1.5ms).
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