Datasheet

DP83630
SNLS335B –OCTOBER 2010–REVISED APRIL 2013 www.ti.com
Table 5-3. LED Mode Selection
Mode LED_CFG[1] LED_CFG[0] LED_LINK LED_SPEED LED_ACT
1 ON for Good Link ON in 100 Mb/s ON for Activity
don't care 1
OFF for No Link OFF in 10 Mb/s OFF for No Activity
2 ON for Good Link ON in 100 Mb/s ON for Collision
0 0
BLINK for Activity OFF in 10 Mb/s OFF for No Collision
3 ON for Good Link ON in 100 Mb/s ON for Full Duplex
1 0
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-TX 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. In 100BASE-TX mode, an optional fast link loss detection may be enabled
by setting the SD_TIME control in the SD_CNFG register. Enabling fast link loss detection will result in the
LED_LINK deassertion within approximately 1.3 µs of loss of signal on the wire.
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).
Activity is defined as configured in LEDACT_RX, bit 8 of register LEDCR (18h). If LEDACT_RX is 0,
Activity is signaled for either transmit or receive. If LEDACT_RX is 1, Activity is only signaled for receive.
The LED_SPEED/FX_SD pin indicates 10 or 100 Mb/s data rate of the port. The standard CMOS driver
goes high when operating in 100 Mb/s operation. The functionality of this LED is independent of mode
selected.
The LED_ACT pin in Mode 1 indicates the presence of either transmit or receive activity. The LED will be
ON for Activity and OFF for No Activity. In Mode 2, this pin indicates the Collision status of the port. The
LED will be ON for Collision and OFF for No Collision.
The LED_ACT pin in Mode 3 indicates Duplex status for 10 Mb/s or 100 Mb/s operation. The LED will be
ON for Full Duplex and OFF for Half Duplex.
In 10 Mb/s half duplex mode, the collision LED is based on the COL signal.
Since these LED pins are also used as strap options, the polarity of the LED is dependent on whether the
pin is pulled up or down.
5.6.1 LEDs
Since the Auto-Negotiation (AN) strap options share the LED output pins, the external components
required for strapping and LED usage must be considered in order to avoid contention.
Specifically, when the LED outputs are used to drive LEDs directly, the active state of each output driver is
dependent on the logic level sampled by the corresponding AN input upon power-up/reset. For example, if
a given AN input is resistively pulled low then the corresponding output will be configured as an active
high driver. Conversely, if a given AN input is resistively pulled high, then the corresponding output will be
configured as an active low driver.
Refer to Figure 5-2 for an example of AN connections to external components. In this example, the AN
strapping results in Auto-Negotiation disabled with 100 Full-Duplex forced.
The adaptive nature of the LED outputs helps to simplify potential implementation issues of these dual
purpose pins.
42 Configuration Copyright © 2010–2013, Texas Instruments Incorporated
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