XRT72L50 Datasheet, PDF(142/471 Page) Exar Corporation – SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

English

English German Russian Spanish Italian Polish Chinese Japanese Korean French Portuguese	Language :

XRT72L50 Datasheet, PDF (142/471 Pages) Exar Corporation – SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

◁

XRT72L50

SINGLE CHANNEL DS3/E3 FRAMER WITH HDLC CONTROLLER

REV. 1.2.1

Ã¡Ã§

4.0 DS3 OPERATION OF THE XRT72L50

The XRT72L50 can be configured to operate in the DS3 Mode by writing a â1â into bit-field 6 within

the Framer Operating Mode register, as illustrated below.

Framer Operating Mode Register (Address = 0x00)

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT2

BIT 1

BIT 0

Local Loop-back DS3/E3 Internal LOS RESET

Enable

R/W

R/W

R/W

R/W

x

1

x

0

Interrupt

Enable Reset

R/W

x

Frame Format

R/W

x

TimRefSel[1:0]

R/W

R/W

x

x

4.1 Description of the DS3 Frames and Associated Overhead Bits

The DS3 Frame contains 4760 bits, of which 56 bits are overhead and the remaining 4704 bits are payload bits.

The payload data is formatted into packets of 84 bits and the overhead (OH) bits are inserted between these

payload packets. The XRT72L50 Framer supports the following two DS3 framing formats:

â¢ C-bit Parity

â¢ M13

Figures 28 and 29 present the DS3 Frame Format for C-bit Parity and M13, respectively.

FIGURE 28. DS3 FRAME FORMAT FOR C-BIT PARITY

X

I

F1

I AIC I

F0

I

NA

I

F0

I FEAC I

F1

I

I

X

I

F1

I UDL I

F0

I

NA

I

F0

I UDL I

F1

I

P

I

F1

I

CP

I

F0

I

CP

I

F0

I

CP

I

F1

I

P

I

F1

I FEBE I

F0

I FEBE I

F0

I FEBE I

F1

I

M0

I

F1

I

DL

I

F0

I

DL

I

F0

I

DL

I

F1

I

M1

I

F1

I UDL I

F0

I UDL I

F0

I UDL I

F1

I

M0

I

F1

I UDL I

F0

I UDL I

F0

I UDL I

F1

I

X = Signaling bit for network control

I = Payload Information (84 bit packets)

Fi = Frame synchronization bit with logic value i

P = Parity bit

Mi = Multiframe synchronization bit with logic value i

AIC = Application Identification Channel

NA = reserved for network application

FEAC = Far End Alarm and Control

DL = Data Link

CP = CP (Path)-bit parity

FEBE = Far End Block Error

129

▷