TLK110 Datasheet, PDF (16/104 Pages) Texas Instruments – Industrial Temp, Single Port 10/100Mbs Ethernet Physical Layer

TLK110
SLLS901A – DECEMBER 2011 – REVISED FEBRUARY 2012
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3.9 LED Interface
The TLK110 supports three configurable Light Emitting Diode (LED) pins. The device supports three LED
configurations: Link, Speed, and Activity. Functions are multiplexed among the LEDs into three modes.
The LEDs can be controlled by configuration pin and/or internal register bits. Bits 6:5 of the LED Direct
Control register (LEDCR) selects the LED mode as described in Table 3-3.
Mode
1
2
3
LED_CFG[1]
(bit 6)
don't care
0
1
Table 3-3. LED Mode Select
LED_CFG[0]
(bit 5) or (pin 22)
1
0
0
LED_LINK
ON for Good Link
OFF for No Link
ON for Good Link
BLINK for Activity
ON for Good Link
BLINK for Activity
LED_SPEED
ON in 100Mbs
OFF in 10Mbs
ON in 100Mbs
OFF in 10Mbs
ON in 100Mbs
OFF in 10Mbs
LED_ACT
ON Pulse for Activity
OFF for No Activity
ON for Collision
OFF for No Collision
ON for Full Duplex
OFF for Half Duplex
The LED_LINK pin in Mode 1 indicates the link status of the port. It is OFF when no link is present. In
Mode 2 and Mode 3 it is ON to indicate that the link is good; BLINK indicates that activity is present on
either transmit or receive channel. The blink rate is controlleded by bits 9:8 of the LEDCR register (0x18).
The default blink rate is 5Hz.
The LED_SPEED pin indicates the data rate of the port, 10Mbs or 100Mbs. This LED is ON when the
device is operating in 100Mbs 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 is ON
(Pulse) for Activity and OFF for No Activity. The width of the pulse is determined by bits 14:13 of the
LEDCR register (0x18). The default pulse width is 200ms. In mode 2 this pin indicates the collision status
of the port. The LED is ON when there is a collision and OFF when there is no collision. In mode 3 this pin
indicates the Duplex status of operation. The LED is ON for Full Duplex and OFF for Half Duplex.
Bits 8:6 of the LEDCR register define the polarity of the signals on the LED pins.
Because the Auto-Negotiation (AN) configuration options share the LED output pins, the external
components required for configuration-pin programming and those for LED usage must be considered in
order to avoid contention.
See Figure 3-6 for an example of AN connections to external components. In this example, the AN
configuration results in Auto-Negotiation with 10/100 Full-Duplex advertised.
AN_EN = 1
AN1 = 1
AN0 = 1
2.2 kW
470 W
2.2 kW
470 W
2.2 kW
470 W
VCC
B0315-01
Figure 3-6. AN Pin Configuration and LED Loading Example
16
Hardware Configuration
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