TLK100_11 Datasheet, PDF (16/88 Pages) Texas Instruments – Industrial Temp, Single Port 10/100 Mb/s Ethernet Physical Layer Transceiver

TLK100
SLLS931B – AUGUST 2009 – REVISED DECEMBER 2009
www.ti.com
3.4 LED Interface
The TLK100 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.
Table 3-3. LED Mode Select
Mode
1
2
3
LED_CFG[1]
(bit 6)
don't care
0
1
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 100 Mb/s
OFF in 10 Mb/s
ON in 100 Mb/s
OFF in 10 Mb/s
ON in 100 Mb/s
OFF in 10 Mb/s
LED_ACT
ON Pulse for Activity
OFF for No Activity
None
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 Link is good and BLINK to indicate activity is present on either
transmit or receive channel. The blink rate is decided by the bits 9:8 of the LEDCR register (0x18). The
default blink rate is 5Hz.
The LED_SPEED pin indicates 10 or 100 Mb/s data rate of the port. This LED is ON when the device is
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 is ON
(Pulse) for Activity and OFF for No Activity. The width of the pulse is determined by the bits 14:13 of the
LEDCR register (0x18). The default pulse width is 200ms. In mode 3 this pin indicates the Duplex status
of operation. The LED is ON for Full Duplex and OFF for Half Duplex.
Bits 2:0 of the LEDCR register defines the polarity of the signals on the LED pins.
Since 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 3-2 for an example of AN connections to external components. In this example, the AN
programming results in Auto-Negotiation with 10/100 Half/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
16
Configuration
VCC
B0315-01
Figure 3-2. AN Pin Configuration and LED Loading Example
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