XRT73L03 Datasheet, PDF (13/62 Pages) Exar Corporation – 3 CHANNEL E3/DS3/STS-1 LINE INTERFCE UNIT

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PRELIMINARY
PIN DESCRIPTION
PIN #
64
SIGNAL NAME
SDO/(E3_Ch1)
65
STS1/DS3_Ch1
66
ICT
67
LOSTHR1
68
LLB1
3 CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT XRT73L03
REV. P1.0.13
TYPE
I/O
I
I
I
I
DESCRIPTION
Serial Data Output from the Microprocessor Serial Interface/E3_Mode
Select - Channel 1:
The function of this pin depends on whether the XRT73L03 is operating in the
HOST Mode or in the Hardware Mode.
HOST Mode Operation - Serial Data Output for the Microprocessor Serial
Interface:
This pin serially outputs the contents of the specified Command Register dur-
ing Read Operations. The data is updated on the falling edge of the SClk input
signal and tri-stated upon completion of data transfer.
Hardware Mode Operation - E3 Mode Select - Channel 1:
This input pin is used to configure Channel 1 in the XRT73L03 to operate in
the E3 or STS/DS3 Modes. Setting this input pin to "High" configures Channel
1 to operate in the E3 Mode. Setting this input pin to "Low" configures Chan-
nel 1 to operate in either the DS3 or STS-1 Modes, depending upon the state
of the STS-1/DS3_Ch1 input pin (pin 31).
NOTE: This pin is internally pulled “Low” when XRT73L03 is in the Hardware
Mode.
STS-1/DS3 Select Input - Channel 1:
“High” for STS-1 and “Low” for DS3 Operation.
The XRT73L03 ignores this pin if the E3_Ch1 pin (pin 28) is set to “1". This
input pin is ignored if the XRT73L03 is operating in the HOST Mode. If the
XRT73L03 is operating in the HOST Mode, the pin should be tied to GND.
In-Circuit Test Input:
Setting this pin "Low" causes all digital and analog outputs to go into a high-
impedance state to allow for in-circuit testing. For normal operation, set this
pin "High".
NOTE: This pin is internally pulled “High".
Loss of Signal Threshold Control - Channel 1:
The voltage forced on this pin controls the input loss of signal threshold for
Channel 1. Forcing the LOSTHR1 pin to GND or VDD provides two settings.
This pin must be set to the desired level upon power up and should not be
changed during operation.
NOTE: This pin is only applicable during DS3 or STS-1 operations.
Local Loop-back - Channel 1:
This input pin along with RLB1 dictates the Loop-Back mode in which Channel
1 in the XRT73L03 is operating.
A "High" on this pin with RLB1 set to "Low" configures Channel 1 of the
XRT73L03 to operate in the Analog Local Loop-back Mode.
A "High" on this pin with RLB1 set to "High" configures Channel 1 of the
XRT73L03 to operate in the Digital Local Loop-back Mode.
NOTE: This input pin is ignored and should be connected to GND if the
XRT73L03 is operating in the HOST Mode.
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