Datasheet
2.2 k:
PHYAD1 = 1PHYAD2 = 0PHYAD3 = 0PHYAD4 = 0
VCC
RXD1_
B
RXD0_B
RXD
1
_
A
RXD
1
_
A
DP83849IF
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SNOSAX8D –JUNE 2009–REVISED APRIL 2013
The DP83849IF can Auto-Negotiate or parallel detect to a specific technology depending on the receive
signal at the PMD input pair. A valid link can be established for the receiver even when the DP83849IF is
in Isolate mode.
Figure 5-1. PHYAD Strapping Example
5.5 LED INTERFACE
The DP83849IF supports three configurable Light Emitting Diode (LED) pins for each port.
Several functions can be multiplexed onto the three LEDs using three different modes of operation. The
LED operation mode can be selected by writing to the LED_CFG[1:0] register bits in the PHY Control
Register (PHYCR) at address 19h, bits [6:5]. In addition, LED_CFG[0] for each port can be set by a strap
option on the CRS_A and CRS_B pins. LED_CFG[1] is only controllable through register access and
cannot be set by as strap pin.
See Table 5-3 for LED Mode selection.
Table 5-3. LED Mode Selection
Mode LED_CFG[1] LED_CFG[0] LED_LINK LED_SPEED LED_ACT/LED_COL
1 don't care 1 ON for Good Link ON in 100 Mb/s ON for Activity
OFF for No Link OFF in 10 Mb/s OFF for No Activity
2 0 0 ON for Good Link ON in 100 Mb/s ON for Collision
BLINK for Activity OFF in 10 Mb/s OFF for No Collision
3 1 0 ON for Good Link ON in 100 Mb/s ON for Full Duplex
BLINK for Activity OFF in 10 Mb/s OFF for Half Duplex
The LED_LINK pin in Mode 1 indicates the link status of the port. In 100BASE-T mode, link is established
as a result of input receive amplitude compliant with the TP-PMD specifications which will result in internal
generation of signal detect. A 10 Mb/s Link is established as a result of the reception of at least seven
consecutive normal Link Pulses or the reception of a valid 10BASE-T packet. This will cause the assertion
of LED_LINK. LED_LINK will deassert in accordance with the Link Loss Timer as specified in the IEEE
802.3 specification.
The LED_LINK pin in Mode 1 will be OFF when no LINK is present.
The LED_LINK pin in Mode 2 and Mode 3 will be ON to indicate Link is good and BLINK to indicate
activity is present on activity. The BLINK frequency is defined in BLINK_FREQ, bits [7:6] of register
LEDCR (18h).
Copyright © 2009–2013, Texas Instruments Incorporated Configuration 35
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