XR72L52 Datasheet, PDF (158/480 Pages) Exar Corporation – TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

XRT72L52
REV. 1.0.1
xr
TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
The behavior of the signal between the XRT72L52 and the Terminal Equipment for DS3 Mode 3 Operation is il-
lustrated in Figure 37.
FIGURE 37. BEHAVIOR OF THE TERMINAL INTERFACE SIGNALS BETWEEN THE XRT72L52 AND THE TERMINAL
EQUIPMENT (DS3 MODE 3 OPERATION)
Terminal Equipment Signals
DS3_Clock_In
DS3_Data_Out
Tx_Start_of_Frame
DS3_Overhead_Ind
Payload[4702] Payload[4703]
X-Bit
Payload[1]
XRT72L5x Transmit Payload Data I/F Signals
TxInClk
TxSer
Payload[4702] Payload[4703]
TxFrame
TxOH_Ind
X-Bit
Payload[1]
DS3 Frame Number N
Note: TxFrame pulses high to denote
DS3 Frame Boundary.
Note: TxOH_Ind pulses high to
denote Overhead Data
(e.g., the X-bit).
DS3 Frame Number N + 1
Note: X-Bit will not be processed by the
Transmit Payload Data Input Interface.
How to configure the XRT72L52 to operate in this mode.
1. Set the NibIntf input pin "Low".
2. Set the TimRefSel[1:0] bit-fields within the Framer Operating Mode Register to "10” or “11" as depicted
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
Enable
R/W
R/W
R/W
0
0
1
RESET
R/W
0
Interrupt
Enable Reset
R/W
1
Frame Format
R/W
0
TimRefSel[1:0]
R/W
R/W
1
X
3. Interface the XRT72L52 to the Terminal Equipment as illustrated in Figure 36.
4.2.1.4 Mode 4 - The Nibble-Parallel/Loop-Timed Mode Behavior of the XRT72L52
The XRT72L52 configured to operate in this mode behaves as follows:
Looped Timing
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