LSF0102: MDO, MDIO level shifter

na na78

Guru 16770 points

Part Number: LSF0102

We suppose to use LSF0102 as a level shifter of MDC and MDIO.

I attach a block diagram image.

Could you please review it and give me a feedback for any concern.

BestRegards

0 Dylan Hubbard over 5 years ago

Hey Na,

Everything looks good so far, I would add bypass caps in the actual schematic. 57 ohms seems a little small, are you expecting high data rates?

0 na na78 over 5 years ago in reply to Dylan Hubbard

Guru 16770 points

Hi Dylan

Thank you for your reply.

I just followed the Table 7 in datasheet.

At least, MDC could be around 25MHz as maximum.

BestRegards

0 Clemens Ladisch over 5 years ago in reply to na na78

Guru 317770 points

You use 57 Ω if you want a current of 15 mA through the pull-up resistor.

Why do you want a 15 mA current? Is the capacitive load so high? Can your drivers even handle this current?

0 na na78 over 5 years ago in reply to Clemens Ladisch

Guru 16770 points

Hi Clemens

Thank you for your reply.

A Driver is normal FPGA, so 5mA current would not be needed actually, larger resistor can be selected.

BestRegards

0 Dylan Hubbard over 5 years ago in reply to na na78

Hey Na,

Yes I recommend using larger resistors especially for that speed. This video below does a great job explaining how properly size the pull-ups:

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