
XRT72L54
á
FOUR CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
REV. P1.1.2
PRELIMINARY
3
PIN DESCRIPTION
PIN #PIN NAME
TYPE
DESCRIPTION
A1
TxLev[1]
O
See Description for Pin C3
A2
EncoDis[1]
O
See Description for Pin B2
A3
RxOOF[0]
O
Receiver "Out of Frame" Indicator:
The Receive Section of the XRT72L54 Framer IC will assert this output
signal whenever it has declared an "Out of Frame" (OOF) condition with
the incoming DS3 or E3 frames. This signal is negated when the framer
correctly locates the framing alignment bits or bytes and correctly aligns
itself with the incoming DS3 or E3 frames.
A4
RxRed[1]
O
See Description for Pin B5
A5
Req[0]
O
Receive Equalization Enable/Disable Select output pin - (to be con-
nected to the XRT7300 DS3/E3 Line Interface Unit IC):
This output pin is intended to be connected to the REQ input pin of the
XRT7300 DS3/E3 (REQDIS or REQEN of the XRT73L03 or XRT
73L04) Line Interface Unit IC. The user can control the state of this out-
put pin by writing a '0' or '1' to Bit 5 (REQ) within the Line Interface
Driver Register (Address = 0x80). If the user commands this signal to
toggle "high" then the internal Receive Equalizer (within the XRT7300
Device) will be disabled. Conversely, if the user commands this output
signal to toggle "low", then the internal Receive Equalizer (within the
XRT7300 Device) will be enabled.
For information on the criteria that should be used when deciding
whether to bypass the equalization circuitry or not, please consult the
"XRT7300 DS3/E3 Line Interface Unit" data sheet.
Writing a "1" to Bit 5 of the Line Interface Drive Register (Address =
0x80) will cause this output pin to toggle "high". Writing a "0" to this bit-
field will cause this output pin to toggle "low".
If the Exar XRT7300 DS3/E3 family of Line Interface Unit IC’s are not
used, then this output pin can be used for other purposes.
A6
LLOOP[1]
O
See Description for Pin C7
A7
RLOOP[1]
O
See Description for Pin B7
A8
ExtLOS[1]
I
See Description for Pin D9
A9
RxOHClk[1]/
RxHDLCClk[1]
O
See Description for Pin D12
A10
TxOHClk[1]
O
See Description for Pin A14
A11
TxOHFrame[1]/
TxHDLCClk[1]
O
See Description for Pin C13
A12
TxOH[1]/
TxHDLCDat5[1]
I
See Description for Pin A15
A13
RxOHFrame[0]/
RxHDLCDat4[0]
O
Receive Overhead Frame Boundary Indicator:
This output pin pulses "high" whenever the Receive Overhead Data
Output Interface” block outputs the first overhead bit (or nibble) of a new
DS3 or E3 frame.
Receive HDLC Data Output - 4:
This pin contains bit 4 RxHDLC data when the HDLC controller is on.