TS3L301: Is magnetics needed while using TS3L301 IC.

HARSHA K

Part Number: TS3L301

Hi Team,

Magnetics are used for protection against faults, transients and common mode signals(caused by EMI, noise picked up by the cable, impedance mismatches) between two transceiver IC's. Magnetics also provide galvanic isolation.

Since EINT is a test jig between two testers as shown in figure. Our EINT board acts like a cable. As shown in image, Tester 1 and Tester 2 device already consists of magnetics, so we havent provided the magentics in EINT as shown in image.

Please find the below image and let us know your feedback whether magnetics is required or in EINT.

over 4 years ago

0 Saminah C over 4 years ago

TI__Genius 9132 points

Hi Harsha,

It is recommended to have magnetics on both ends of an Ethernet-link - You are providing that in the two testers on either side so you should not need a magnetic in EINT.

To keep the device safe, it would be best to drive the Ethernet lines low whenever it is not being powered.

Regards

Saminah

0 HARSHA K over 4 years ago in reply to Saminah C

Prodigy 170 points

Hi Saminah,

Thank you for the support.

We are also few queries on how to DC shift the signal without distorting the positive cycle. We have pulled up lines to 100R and found that positive signal is getting distorted. Please find the below image for reference. Please suggest how to do DC biasing for the Ethernet lanes.

0 Saminah C over 4 years ago in reply to HARSHA K

TI__Genius 9132 points

HI Harsha,

I am going to loop in the Ethernet team to guide you on this - The TS3L301 was not designed to handle a negative swing.

Regards

Saminah

0 HARSHA K over 4 years ago in reply to Saminah C

Prodigy 170 points

Hi Team,

We are waiting for your guidance on the biasing of the Ethernet lanes. Could you please prioritize it?

Regards,

Harshavardhan.K

0 Justin Lazaruk over 4 years ago in reply to HARSHA K

TI__Expert 7040 points

Hi Harshavardhan,

The pull-up resistor placed in the DC biasing block of your block diagram above should not have any affect on the Ethernet data-lines seen by the PHY. The magnetic components in "Tester 1" and "Tester 2" will decouple the DC offset seen by the PHY.

Can you describe the distortion you are observing and where the signal is being probed?

Regards,

Justin

0 HARSHA K over 4 years ago in reply to Justin Lazaruk

Prodigy 170 points

Hi Justin,

Thank you for the support.

We will get back to you if there are any issues.

Regards,
Harshavardhan.K

0 HARSHA K over 4 years ago in reply to HARSHA K

Prodigy 170 points

Hi Justin,

We are biasing the Ethernet lines by pulling up resistor to 3.3V. Due to this, the I/O volatge levels at the input side of switch will swing from 4.3V to 0V but we are operating the TS3L301 at 3.3V supply. I hope this will not effect the functionality of IC and the signal data coming outside of the switch will not be lost.

Note: As per the datasheet, the I/O voltage level of the switch is 5V. Could you please explain how this can be achieved?

Awaiting for your early response.

Regards,
Harshavardhan.K

0 HARSHA K over 4 years ago in reply to HARSHA K

Prodigy 170 points

Hi Justin,

Could you please prioritize and let me know your inputs on the same?

Regards,
Harshavardhan.K

0 Justin Lazaruk over 4 years ago in reply to HARSHA K

TI__Expert 7040 points

Hello Harshavardhan,

I will loop in the switches team again to comment on this.

Regards,

Justin

0 Saminah C over 4 years ago in reply to Justin Lazaruk

TI__Genius 9132 points

Hello Harshavardhan,

If the TS3L301 is operating at 3.3V supply, you can pass input voltage upto 5.5V without any issue.

Regards

Saminah

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TS3L301: Is magnetics needed while using TS3L301 IC.