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5

Handset

PoE chip

IC9

nRST_PHY

nRST_PHY

JK1

JK2

X1

TX_CLK

RxRDY,OP_DET,SCLK,

RxD,TxD, RESET_OUT

DC/DC

+4V

+3.3V

+1.5V

REG(1.5V)

25.00

MHz

PULSE

Trans

T2

RJ45

Super

CAP

To LAN

10/100Base-t

To PC

10/100Base-t

RJ45

PULSE

Trans

T1

X2

REG(3.3V)

+9V

DC IN

DC ALARM

CN2

(For Option)

IC10,31

IC11

C501

C502

TX_EN,TX_ER,

TXD[3:0],

CRS

TX_CLK

RX_DV

RX_ER

RXD[3:0],

RX_CLK

COL

Ethernet

PHY

(KSZ8041)

IC6

MAC1

MII2

TX_EN,TX_ER,

TXD[3:0],

CRS

RX_DV

RX_ER

RXD[3:0],

RX_CLK

COL

Ethernet

PHY

(KSZ8041)

IC7

MAC2

MII1

BK_LIT

Data Bus

Bluetooth unit

<LCD_Boad>

SIO

GPIO

CN603

PCMSYNC1,PCMOUT,

PCMIN,PCMCLK

CN

604

CN

602

PIO[3:0],RESET,

UART_TX/RX,UART_RTS/CTS

IC28

IC27

IC27

IC25

IC24

Q1

IC26

IC26

IC20

IC20

IC26

SW

IC30

IC23

IC21

IC28

SW

HSIN

HSOUT

MICIN

SPOUT

MUTE_SP0

MUTE_SP1

MUTE_SP2

IC29

PCM_I/F

GPIO

CPU(Slave)

IC8

IC13

IC12

TXD,RESET,

RXD_SUB,SCLK_SUB

LED / Key

IC4

SDRAM

8Mbyte

FLASH

4Mbyte

MIC

Speaker

VoIP/DSP

Address Bus

Reset

IC

+48V

8.192

MHz

INT

CN5

CN4

Analog

IF

IC1

JK5

RJ11

JK4

HeadSet IF

RESETn

Transistor

SW

SW

SW

SW

SW

SW

IC3

IC2

KX-NT343

RU

/KX-NT343

RU

-B Block Diagram

Eth

ern

et

 I/

F

KEY

/LE

D/

LCD

Ana

log

 I

/F

 

Pow

er I/

F

 

CN

601

CN

9

LCD

Back

light

6

The DSP , MAC, CODEC and the CPU are built into the VoIP (IC1).  
The FLASH (IC2) and the SDRAM (IC3) are connected to the CPU. The contents of the FLASH are expanded to the SDRAM at
start-up. It also stores each setting.  
If the LCD is not displayed in the operation but there is no problem on the LCD, then the failure of the CPU system memory (IC2
and IC3) should be considered.

LCD data are outputted from pin 54 of IC4 to LCD module.
IC19 is an inverter for a charge pump circuit which outputs the voltage necessary for LCD driving.

• 4.5V from -1.2V generated at IC19 as a reference to +3.3V of the power supply voltage is pressurized four times in the LCD mod-

ule and used as LCD driving voltage (approx. 18V).

LCD contrast is set by electronic volume in the LCD module.
The type of the LCD module is distinguished by pin 56 of IC4.
KX-NT343 uses a 24 digits x 3 lines LCD.

The lighting of the backlight is controlled by Q601.

• IC4-pin 52 H

→Q601-ON→Backlight ON

• IC4-pin 52 L

→Q601-OFF→Backlight OFF

7

Reset Signal is outputted from IC12 and inputted into IC1 and IC2.

The Ethernet hub IC (IC6, IC7) is used for the Ethernet interface.
It is connected from IC6 to the Ethernet port (JK2) through a transformer and so is  isolated.
Also, LAN port (JK2) gets power from the Ethernet line for PoE (Power over Ethernet) as shown below.
It is connected between IC7 and the VoIP (IC1) by high-speed bus called MII (Media Independent Interface) bus operating with
25MHz.

8

This circuit performs the setting of the call path/vol. adjustment in each call mode by a built-in DSP of VoIP(IC1).The audio gain
of each call is determined by download data from PBX or by internal data from flash memory(IC2).
In case of the extension call between NT300, The telephone call becomes a characteristic in accordance with G722.

1. Handset Call

Transmitting signal is inputted from handset microphone, and amplified by IC24 and IC25 

→

 Inputted to IC1-pin112 

→ A/D conversion and Gain adjustment by a built-in DSP of IC1 → then sent to PBX.

Transmitting signal inputted from handset microphone is controlled by transmission switching SW IC27 as follows; 
IC27-pin11 L: Handset Call
(IC27-pin11 H: Headset Call)
Transmitting signal inputted from PBX 

→Gain adjustment by a built-in DSP.

Receiving signal inputted from PBX 

→ Gain adjustment by a built-in DSP of IC1 → D/A conversionand outputted from IC1-

pin115. 

→ Amplified by IC20, and outputted to handset.

2. Headset Call

Transmitting signal is inputted from headset microphone, and amplified by IC24 and IC25 

→ Inputted to IC1-pin112 → A/D

conversion and Gain adjustment by a built-in DSP of IC1 

→ then sent to PBX.

Transmitting signal inputted from headset microphone is controlled by transmission switching SW IC27 as follows;
 IC27-pin11 H: Headset Call
 (IC27-pin11 L: Handset Call)

Receiving signal inputted from PBX 

→ Gain adjustment by a built-in DSP of IC1 → D/A conversion and outputted from IC1-

pin115.

→ Amplified by IC20, and outputted to headset.

3. Speakerphone Call

Speakerphone call realize all double-call by a built-in DSP(echo-canceller)of IC1. For a call In the most appropriate condition,
DSP checks voice level of the calling party, acoustics in a room, voice level of the other party and state of the line of contact,
and cancels echo in transmitting and receiving at the start of calling. It operates in a half double-call state in a few seconds for
the check.

Transmitting signal is inputted from microphone and amplified by IC23

→inputted to IC1-pin113 → A/D conversion and Gain

adjustment by a built-in DSP of IC1, then sent to PBX through echo canceller.

Receiving signal inputted from PBX 

→ Gain adjustment by DSP through a built-in echo canceller of IC1 → D/A conversion

and outputted from IC1-pin116 

→ Amplified by IC21 and outputted to Speaker.

 Power Amp IC21 is controlled as follows;
 IC21-pin1 L: ON
 IC21-pin1 H: OFF