KSZ8851-16MLLJ_10 MICREL [Micrel Semiconductor], KSZ8851-16MLLJ_10 Datasheet - Page 37

• Manufacturer Part Number: KSZ8851-16MLLJ_10
• Description: Single-Port Ethernet MAC Controller with 8-Bit or 16-Bit Non-PCI Interface
• Manufacturer: MICREL [Micrel Semiconductor]

Micrel, Inc.
KSZ8851-16MLLJ
Loopback Support
The KSZ8851-16MLLJ provides two loopback modes, one is Near-end (Remote) loopback to support for remote
diagnostic of failure at line side, and the other is Far-end (Local) loopback to support for local diagnostic of failure at host
side. In loopback mode, the speed at the PHY port will be set to 100BASE-TX full-duplex mode.
Near-End (Remote) Loopback
Near-end (Remote) loopback is conducted at PHY port 1 of the KSZ8851-16MLLJ. The loopback path starts at the PHY
port’s receive inputs (RXP1/RXM1), wraps around at the same PHY port’s PMD/PMA, and ends at the PHY port’s transmit
outputs (TXP1/TXM1).
Bit [9] of register P1SCLMD (0xF4) is used to enable near-end loopback. The ports 1 near-end loopback path is illustrated
in the following Figure 10.
Far-End (Local) Loopback
Far-end (Local) loopback is conducted at Host of the KSZ8851-16MLLJ. The loopback path starts at the host port’s
transmit inputs (Tx data), wraps around at the PHY port’s PMD/PMA, and ends at the host port’s receive outputs (Rx data)
Bit [14] of register P1MBCR (0xE4) is used to enable far-end loopback at host side. The host far-end loopback path is
illustrated in the following Figure 10.
Figure 10. PHY Port 1 Near-End (Remote) and Host Far-End (Local) Loopback Paths
March 2010
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M9999-030210-1.0