W6691CD Просмотр технического описания (PDF) - Winbond

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W6691CD

ISDN S/T Interface Transceiver

Winbond 

Preliminary W6691

The peripheral simple I/O is used to control other peripheral devices such as CODEC, SLIC, DTMF detector,

LEDs.

7.1.2 Interface and Operating Modes

The W6691 can be configured for the following application:

l ISDN terminals --- TE mode (M1=0 & M0=0)

l ISDN subscriber line termination --- LT-S mode (M1=1 & M0=0)

l ISDN trunk line termination ---LT-T mode (M1=0 & M0=1)

TE , LT-S and LT-T modes are configured by setting mode pins (M1 and M0).

7.2.1 S/T Interface Transmitter/Receiver

According to ITU-T I.430, pseudo-ternary code with 100% pulse width is used in both directions of

transmission on the S/T interface. The binary "1" is represented by no line signal (zero volt), whereas a binary

"0" is represented by a positive or negative pulse.

Data transmissions on the S/T interface are arranged as frame structures. The frame is 250 µs long and

consists of 48 bits, which corresponds to a 192 kbit/s line rate. Each frame carries two octets of B1 channel,

two octets of B2 channel and four D channel bits. Therefore, the 2B+D data rate is 144 kbit/s. The frame

structure is shown in Fig.7.1.

The frame begin is marked by a framing bit, which is followed by a DC balancing bit. The first binary "0"

following the framing bit balancing bit is of the same polarity as the framing bit balancing bit, and subsequent

binary zeros must alternate in polarity.

Publication Release Date: Sep 2001

20

Revision 1.1

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