IDT77V1254L25PG IDT, Integrated Device Technology Inc, IDT77V1254L25PG Datasheet - Page 29

• Manufacturer Part Number: IDT77V1254L25PG
• Manufacturer: IDT, Integrated Device Technology Inc

Specifications of IDT77V1254L25PG

• Data Rate: 25.6/51.2Mbps
• Number Of Channels: 4
• Type Of Atm Phy Interface: DPI/UTOPIA
• Operating Supply Voltage (typ): 3.3V
• Operating Supply Voltage (min): 3V
• Operating Supply Voltage (max): 3.6V
• Operating Temp Range: 0C to 70C
• Operating Temperature Classification: Commercial
• Pin Count: 144
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Not Compliant

Loopback
ters:
transmission by the PMD. Receive data from the PMD is decoded along with its clock for transfer to the receiving "upstream system".
receive interface. Note that while this mode is operating, no data is forwarded to or received from the line interface. Line Loopback
probably be entered under direction from another system (at a remote location), receive data is also decoded and transferred to the upstream system
to allow it to listen for commands. A common example would be a command asking the upstream system to direct the TC to leave this loopback state,
and resume normal operations.
IDT77V1254L25
There are two loopback modes supported by the 77V1254L25. The loopback mode is controlled via bits 1 and 0 of the Diagnostic Control Regis-
Normal Mode
This mode, Figure 32, supports normal operating conditions: data to be transmitted is transferred to the TC, where it is queued and formatted for
PHY Loopback
As Figure 33 illustrates below, this loopback mode provides a connection within the PHY from the transmit PHY-ATM interface to the PHY-ATM
Line Loopback
Figure 34 might also be called “remote loopback” since it provides for a means to test the overall system, including the line. Since this mode will
ATM Layer Device
ATM Layer Device
0
1
1
Bit 1
TC sublayer
TC sublayer
Figure 33 PHY Loopback
Figure 32 Normal Mode
0
0
1
Bit 0
29 of 48
Normal operating mode
PHY Loopback
Line Loopback
Mode
IDT77V1254
77V1254L25
IDT77V1254
77V1254L25
PMD sublayer
PMD sublayer
Interface
3505 drw 33
December 2004
Interface
3505 drw 34
Line
Line