LSF0102: LSF0102 VRef issue

user4979899

Expert 3080 points

Part Number: LSF0102

we do the power simulation: IR drop, and the result is fail.

I believe the VRef pin shall connect to Vcc directly as my understanding.

Also attached schematic, could you please help to double check my design is correct or not?

over 7 years ago

0 ShreyasRao over 7 years ago

TI__Guru 62710 points

Hi Anne,

The 200k biasing resistor is correctly represented in both the datasheet and your schematic. You can watch the LSF training series video regarding biasing LSF training.ti.com/TLM-LSF-Bias

I would recommend removing the series 33ohm resistor on the A and B ports which may not be necessary. what is the speed of the MDIO interface operation?
If you could please send the scope shot of the fail, it will be helpful.

0 user4979899 over 7 years ago in reply to ShreyasRao

TI__Expert 3080 points

Hi Shreyas,

The MDIO max data rate is 12GHz, FYI
And we will have 6 device in A1, A2 pin,
Is it available?

0 ShreyasRao over 7 years ago in reply to user4979899

TI__Guru 62710 points

Thanks, Anne.
MDIO open drain interface at 12Ghz is not possible. The actual speed has to be much less in the Mbps range.
The LSF can work up to 100Mhz with strong pull-up resistors at the IO.

0 user4979899 over 7 years ago in reply to ShreyasRao

TI__Expert 3080 points

Sorry for the typo error, it maximum data rate is 12"M"Hz
And we will have 6 devices in A1, A2 pin, is it available?
How to design the pull up resistor value, please recommend,
Thank you

0 ShreyasRao over 7 years ago in reply to user4979899

TI__Guru 62710 points

Hi Anne,

12Mhz makes more sense with the LSF operation. Stronger pullup resistor would be required for ensuring that the output is rising to the desired voltage level overcoming the fanout loading.

Please watch the video regarding the LSF up translation here.
training.ti.com/TLM-LSF-Basics

and the up translation here:
training.ti.com/TLM-LSF-Up

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LSF0102: LSF0102 VRef issue