XRT75R03D datasheet(27/134 Pages) EXAR

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XRT75R03D

THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER

REV. 1.0.2

SClk/TCLKINV

Microprocessor Serial Interface -Serial Clock Input:

This input pin functions as the Clock Source for the Microprocessor Serial Inter-

face.

Each time the user wishes to perform a READ or WRITE operate with the on-

chip Command Registers via the Microprocessor Serial Interface, the user

MUST do the following.

• Assert the CS input pin by toggling it "Low", and

• Provide 16 Clock Periods to this particular input pin for each READ and

WRITE operation.

The Microprocessor Serial Interface will sample any data residing upon the SDI

input pin, upon the rising edge of this clock signal. Further, for READ opera-

tions, the Microprocessor Serial Interface will serially output the contents of a

target Command Register upon the falling edge of this clock signal.

NOTE: The maximum frequency of this particular clock signal is 10MHz.

CS/RCLKINV

Microprocessor Serial Interface - Chip Select Input:

This input pin should be pulled "Low" whenever a READ or WRITE operation is

to be executed to the on-chip Command Registers, via the Microprocessor

Serial Interface.

This input pin should remain "Low" until the READ or WRITE operation has

been completed. This input pin should be pulled "High" at all other times.

NOTE: If the XRT75R03D has been configured to operate in the Host Mode

then this input pin will function as the RCLKINV input pin.

INT/LOSMUT

Microprocessor Serial Interface - Interrupt Request Output:

If the XRT75R03D has been configured to operate in the Host Mode, then this

pin becomes the Interrupt Request Output for the XRT75R03D.

During normal conditions, this output pin will be pulled "High". However, if the

user enables certain interrupts within the device, and if those conditions occur,

then the XRT75R03D will request an interrupt from the Microprocessor by tog-

gling this output pin "Low".

NOTES:

If the XRT75R03D is configured to operate in the Hardware Mode,

then this pin functions as the LOSMUT input pin.

This pin will remain "Low" until the Interrupt has been served.

101

RESET

Microprocessor Serial Interface - H/W RESET Input:

Pulsing this input "Low" causes the XRT75R03D to reset the contents of the on-

chip Command Registers to their default values. As a consequence, the

XRT75R03D will then also be operating in its default condition.

For normal operation pull this input pin to a logic "High".

NOTE: This input pin is internally pulled high.

MICROPROCESSOR SERIAL INTERFACE - (HOST MODE)

PIN #SIGNAL NAME

TYPE

DESCRIPTION

XRT75R03D Datasheet(PDF) 27 Page - Exar Corporation

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