Dell 2145cn Service Manual page 37

18) FAX section
Block Diagram
Main Board Interface
20pin Connector
5V
CML
3.3V
GND
RXD
TXD
nCTS
nRTS
nDCD
ESC
nRI
nINT
nRESET
XTALO
4.9152
CLKI /XTALI
HANDSET
4pin Connector
nRESET
MBIAS
MIC
SPKRR
SPKRL
Implemented by based on the silicon DAA (Data Access Arrangement) Solution, and is roughly composed
of two Chip Solution
• SI2435(SSD) A Modem Chip which embeds SSD (System Side Device) for interfacing between
LSD and Voice Codec(SI3000)
• SI3018 (LSD) A LIU (Line Interface Unit) Chip which is controlled by SSD and satisfies each PSTN
Requirements by modulating internal Configuration with connecting Tel Line.
Product spec and feature
BLOCK DIAGRAM
5V
VOL_0~VOL_2
MC34119
KEYCLICK
SPK_CTL
AOUT
Si2435
RAM/ROM
Serial
Interface
Microcontroller
DAA
DSP
Interface
PLL Codec
Clocking
Interface
CLKOUT SDI SDO nFSYNC
MCLK SDI SDO nFSYNC
Si3000
Voic Codec
2-26
SPKER
SPK_OUT
5V
CML
Si3018
RX
IB
SC
Hybrid and
DCT
dc
VREG
Termination
VREG2
DCT2
Isolation
DCT 3
Interface
RNG1
RNG2
Ring
QB
Detect
QE
Off-Hook
QE 2
Isolation
Barrier
External
Circuitry
Tel
Line
Ext.
Line