KSZ9031RNX Просмотр технического описания (PDF) - Micrel

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KSZ9031RNX

Gigabit Ethernet Transceiver with RGMII Support

Micrel 

Micrel, Inc.

KSZ9031RNX

For 1000Base-T mode, auto-negotiation is always required to establish a link. During 1000Base-T auto-negotiation, the

master and slave configuration is first resolved between link partners. Then the link is established with the highest

common capabilities between link partners.

Auto-negotiation is enabled by default after power-up or hardware reset. After that, auto-negotiation can be enabled or

disabled through Register 0h, Bit [12]. If auto-negotiation is disabled, the speed is set by Register 0h, Bits [6, 13] and the

duplex is set by Register 0h, Bit [8].

If the speed is changed on the fly, the link goes down and auto-negotiation and parallel detection initiate until a common

speed between KSZ9031RNX and its link partner is re-established for a link.

If the link is already established and there is no change of speed on the fly, the changes (for example, duplex and pause

capabilities) will not take effect unless either auto-negotiation is restarted through Register 0h, Bit [9], or a link-down to

link-up transition occurs (that is, disconnecting and reconnecting the cable).

After auto-negotiation is completed, the link status is updated in Register 1h, Bit [2], and the link partner capabilities are

updated in Registers 5h, 6h, 8h, and Ah.

The auto-negotiation finite state machines use interval timers to manage the auto-negotiation process. The duration of

these timers under normal operating conditions is summarized in Table 2.

Table 2. Auto-Negotiation Timers

Auto-Negotiation Interval Timers

Time Duration

Transmit burst interval

Transmit pulse interval

16ms

68µs

FLP detect minimum time

FLP detect maximum time

Receive minimum burst interval

Receive maximum burst interval

17.2µs

185µs

6.8ms

112ms

Data detect minimum interval

Data detect maximum interval

NLP test minimum interval

NLP test maximum interval

35.4µs

95µs

4.5ms

30ms

Link loss time

Break link time

Parallel detection wait time

Link enable wait time

52ms

1480ms

830ms

1000ms

10/100 Speeds Only

Some applications require link-up to be limited to 10/100Mbps speeds only.

After power-up/reset, the KSZ9031RNX can be restricted to auto-negotiate and link-up to 10/100Mbps speeds only by

programming the following register settings:

1. Set Register 0h, Bit [6] = ‘0’ to remove 1000Mbps speed.

2. Set Register 9h, Bits [9:8] = ‘00’ to remove Auto-Negotiation Advertisements for 1000Mbps full/half duplex.

3. Write a ‘1’ to Register 0h, Bit [9], a self-clearing bit, to force a restart of Auto-Negotiation.

Auto-Negotiation and 10Base-T/100Base-TX speeds use only differential pairs A (pins 2, 3) and B (pins 5, 6). Differential

pairs C (pins 7, 8) and D (pins 10, 11) can be left as no connects.

May 14, 2015

21

Revision 2.2

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