W6691CD Просмотр технического описания (PDF) - Winbond

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W6691CD

ISDN S/T Interface Transceiver

Winbond 

Preliminary W6691

7. FUNCTIONAL DESCRIPTIONS

7.1.1 Main Block Functions

The functional block diagram of W6691 is shown in Fig.6.1. The main function blocks are:

- Layer 1 function according to ITU-T I.430

- B channel switching

- GCI bus interface

- PCM port (x 2) and internal B channel switching

- D channel HDLC controller

- DPLL 2 circiut generating 4.096 MHz clock for NT2 application

The layer 1 function includes:

- S/T bus transmitter/receiver

- Timing recovery using Digital Phase Locked Loop (DPLL) circuit

- Layer 1 activation/deactivation

- D channel access control

- Frame alignment

- Multi-frame synchronization

- Test functions

The serial interface bus performs the multiplexing/demultiplexing of D and 2B channels.

The B channel switching determines the connection between layer 1/GCI, layer 2 and PCM.

GCI bus is for TE, LT-S and LT-T mode applications.

The PCM port provides two 64 kbps clear channels to connect to PCM codec chips.

The D channel HDLC controller performs the LAPD (Link Access Procedure on the D channel) protocol

according to ITU-T I.441/Q.921 recommendation.

Publication Release Date: Sep 2001

19

Revision 1.1

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