ksz8051mlli Micrel Semiconductor, ksz8051mlli Datasheet - Page 15

• Manufacturer Part Number: ksz8051mlli
• Description: 10base-t/100base-tx Physical Layer Transceiver
• Manufacturer: Micrel Semiconductor

Micrel, Inc.
Scrambler/De-Scrambler (100Base-TX Only)
The scrambler is used to spread the power spectrum of the transmitted signal to reduce EMI and baseline wander, and
the de-scrambler is needed to recover the scrambled signal.
SQE and Jabber Function (10Base-T Only)
In 10Base-T operation, a short pulse is put out on the COL pin after each frame is transmitted. This SQE Test is required
as a test of the 10Base-T transmit/receive path. If transmit enable (TXEN) is high for more than 20 ms (jabbering), the
10Base-T transmitter is disabled and COL is asserted high. If TXEN is then driven low for more than 250 ms, the 10Base-
T transmitter is re-enabled and COL is de-asserted (returns to low).
PLL Clock Synthesizer
The KSZ8051MLL generates all internal clocks and all external clocks for system timing from an external 25MHz crystal,
oscillator, or reference clock.
Auto-Negotiation
The KSZ8051MLL conforms to the auto-negotiation protocol, defined in Clause 28 of the IEEE 802.3 Specification.
Auto-negotiation allows UTP (Unshielded Twisted Pair) link partners to select the highest common mode of operation.
During auto-negotiation, link partners advertise capabilities across the UTP link to each other, and then compare their own
capabilities with those they received from their link partners. The highest speed and duplex setting that is common to the
two link partners is selected as the mode of operation.
The following list shows the speed and duplex operation mode from highest to lowest priority.
If auto-negotiation is not supported or the KSZ8051MLL link partner is forced to bypass auto-negotiation, then the
KSZ8051MLL sets its operating mode by observing the signal at its receiver. This is known as parallel detection, and
allows the KSZ8051MLL to establish link by listening for a fixed signal protocol in the absence of auto-negotiation
advertisement protocol.
Auto-negotiation is enabled by either hardware pin strapping (NWAYEN, pin 42) or software (register 0h, bit 12).
By default, auto-negotiation is enabled after power-up or hardware reset. Afterwards, auto-negotiation can be enabled or
disabled by register 0h, bit 12. If auto-negotiation is disabled, the speed is set by register 0h, bit 13, and the duplex is set
by register 0h, bit 8.
The auto-negotiation link up process is shown in Figure 1.
July 2010
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Priority 1: 100Base-TX, full-duplex
Priority 2: 100Base-TX, half-duplex
Priority 3: 10Base-T, full-duplex
Priority 4: 10Base-T, half-duplex
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M9999-071210-1.0
KSZ8051MLL