Dell 2355DN Service Manual page 21

Signal Transition of DAA Solution
1) Line Interface Signal of Tel Line and LSD is Analog Signal.
2) there is A/D, D/A Converter in LSD, so Analog Signal from Tel Line is converted in Digital through A/D
Converter in DAA and transfer to SSD by DIB Capacitor Digital Signal from SSD is converted to Analog by
D/A Converter in DAA and transfer to Tel Line
3) Transformer transfer Clock from SSD to LSD and Clock Frequency is 4.032MHz.
LSD full wave rectifies Clock to use as inner Power supply and also use as Main Clock for DIB Protocol
Sync between LSD and SSD. Transformer transfer Clock by separating Primary and Secondary, and
amplifies Clock Level to LSD by Coil Turns Ratio 1:1.16.
■ Clock
- Clock is supplied by transformer from SSD to LSD, and there is PWROUT to adjust output impedance of
Clock
SSD
Out Driver is inside SSD and CLKSHIGH Resistor to adjust duty of HLPWR Resistor and Clock.
Clock from SSD to LSD has Differential structure of 180 phase difference for Noise Robustness DIB Data
transfer Data from SSD to LSD by Transformer, and also transfer specific data from LSD to SSD.
After transferring data from SSD, RSP is transferred and LSD recognizes RSP and change LSD to output
Driver transfer Data to SSD.
DIB Data form SSD to LSD by Transformer has Differential structure of 180 phase difference between DIBP
and DIBN for Noise Robustness
Service Manual
Product spec and feature
CLKP
CLKN
DIBP
DIBN
2-12
LSD