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Circuit Description
5-1-7 Modem and TX-and RX Related
Circuits
M O D E M
T h e s e c i rc u i t s c o n t rol signal transmission between the
internal modem and the LIU or a remote modem. The
KS16117 modem is a signal-chip fax-modem having
f e a t u res to detect and generate DTMF tones. TX OUT
(pin44) is the modem output port, and RXIN (pin45) is
the input port. /PORI (pin67) from KS32C6100 is the
signal which enables modem initialization at system
power on.
D0~D7 (pin8-15) are the data bus RS0-RS4 (pin56~60)
a re i n t e r n a l resister select signals which determine the
mode.
/CS (pin54) is chip select, /RD (pin55), /WR (pin53)
a re read and write contro l s i g n a l s . / I R Q ( p i n 5 2 ) i s
modem interrupt output signal. The transmission
speed of KS16117 is maximum 14.4 Kbps.
5-18
TRANSMIT CIRCUIT
T h i s c i rc u i t c o n t rols transmission of analog signals
f rom the modem (KS1611 7 ) .
Output voltage from the modem (TXOUT: 4 4 ) i s
buff e re d t h rough LIU board and OP-AMP a f t e r s i g n a l
s m o o t h i n g a n d f i l t e r i n g , a n d f i n a l l y o u t p u t t o t h e l i n e .
RECEIVE CIRCUIT
I n receive mode, analog signals from the LIU board a re
amplified and transferred to RXIN:45 through the
smoothing filter.
Fig.5-10 TX and RX Part
Samsung Electronics
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