L-ET1011C2-CI-D LSI, L-ET1011C2-CI-D Datasheet - Page 9

• Manufacturer Part Number: L-ET1011C2-CI-D
• Manufacturer: LSI

Specifications of L-ET1011C2-CI-D

• Number Of Receivers: 1
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Operating Temperature (max): 85C
• Operating Temperature (min): -40C
• Lead Free Status / Rohs Status: Compliant

September 2007
LSI Corporation
Functional Description
Loopback Mode
Enabling loopback mode allows in-circuit testing of the ET1011C's digital and analog data path.
The ET1011C provides several options for loopback that test and verify various functional blocks within the PHY. These are
digital loopback and analog loopback. Figure 2 is a block diagram that shows the PHY loopback functionality.
The loopback mode is selected by setting the respective bit in the PHY loopback control register, MII register address 19. The
default loopback mode is digital MII loopback. Loopback is enabled by writing to the PHY control register, address 0, bit 14.
Digital Loopback
Digital loopback provides the ability to loop the transmitted data back to the receiver via the digital circuitry. The point at
which the signal is looped back is selected using the loopback control register with the following options being provided: MII
and all digital. Selecting the MII option gives a simple loopback with minimal latency where the data is looped back directly
at the media-independent interface. This loopback is currently set as the default, but it should be noted that it only exercises a
small percentage of the PHY circuitry. When the all-digital option is selected, the transmitted data is looped back at the inter-
face between the digital and the analog circuitry, thereby exercising a high percentage of the digital logic. Figure 3 shows a
block diagram of digital loopback.
Switch
MAC /
Switch
MAC /
(continued)
MII Loopback
G
M
I
I
All Digital Loopback
Figure 2. Loopback Functionality
Figure 3. Digital Loopback
M
G
I
I
Digital
PHY
Digital
PHY
PHY
AFE
Replica Loopback
PHY
AFE
Gigabit Ethernet Transceiver
Line Driver Loopback
Remote
PHY
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