Hello !
We use a device containing tlk110-based network interface. In normal operation, everything works successfully. However, we noticed the following unexpected behavior: if the device is de-energized (all connections except the network are disconnected, no battery power), the network hub (Surecom Etherperfect 508t, 10mbit only) recognizes it as an active 10base-device.
We investigated the behavior of the network and found that tkl110, in the absence of power, freely transmits a signal from Rx to Tx and vice versa, weakening it slightly (2 volts pulse -> 0.2 volts). The network hub "hears" its own request and mistakenly detects device as 10base.
We investigated several different network controllers from different manufacturers, but did not find a similar echo effect when the devices was de-energized.
We also checked the tlk110 datasheet and also did not find any significant errors in our electric curcuit. PulseJack JX30-0005nl is used as separation transformer.
Unfortunately, the erroneous identification of a de-energized device leads to switch port on at network hub, which can lead to the occurrence of loopback, which some network equipment recognizes as a failure.
What can we check or change in the circuitry of the device to avoid echoes?
