KX-NT543RU, KX-NT543RU-B, KX-NT546RU, KX-NT546RU-B (serv.man2) - Panasonic PBX Service Manual (repair manual). Page 8

8

The PHY IC (IC401) is used for the Ethernet interface.
It is connected from IC401 to the Ethernet port (JK401) through a transformer and so is  isolated.
Also, LAN port (JK402) gets power from the Ethernet line for PoE (Power over Ethernet) as shown below.
It is connected between IC401 and the BBIC (IC501) by high-speed bus called MII (Media Independent Interface) bus operating
with 25MHz.

1. Speaker phone call

Transmitting signal is input from microphone and amplified by IC103 

→ input to IC501-pin G2 → A/D conversion, Gain adjust-

ment and echo cancel by a built-in DSP of IC501.
Receiving signal input from IP Line 

→ Gain adjustment and D/A conversion by DSP of IC501 → output from IC501-pin E1,F1

→ Amplified by IC101 and output to Speaker.
Class D Amp IC101 is controlled as follows;
IC101-pin1 H (3.3V): Amp ON , IC101-pin1 L (0V): Amp OFF

+

-

MIP

AG3

OPBIAS

SPP

SPN

SPAMPEN

C117

5V

AG3

MICBIAS

C134

R101
R102

R130

R131

SPP

SPN

MIP

MIN

L101

L102

IC103

3

2

1

C122

C110

R124

R125

C129

C130

R126

R127

C111

C101
C102

C135

AG3

L103

L104

D108

DL101

1

2

3

C174

C175

C121

C118

C176

C177

C123

C126

C138

DG

DG

DG

DG

DG

DG

DG

DG

DG

DG

C182

C183

C184

R109

R152

C185

AG3

C105

IC101

1 STBY

2 NC

3 IN+

4 IN-

5

OUT+

6

VDD

7

GND

8

OUT-

9

FIN

CL103

CL104

CL106

CL105

DG

DG

C191

C190

C192

C193

AG3

AG3

R118

R119

D107

D101

D102

IC501

BBIC

E3

F1

E1

G2