W6691CD WINBOND [Winbond], W6691CD Datasheet - Page 19

• Manufacturer Part Number: W6691CD
• Description: ISDN S/T Interface Transceiver
• Manufacturer: WINBOND [Winbond]

7. FUNCTIONAL DESCRIPTIONS
7.1.1 Main Block 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.
The functional block diagram of W6691 is shown in Fig.6.1. The main function blocks are:
The layer 1 function includes:
- 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
- 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
19
Preliminary W6691
Publication Release Date: Sep 2001
Revision 1.1