TUSB9261DEMO: USB2_1P1V and VDDA_1P8V voltage rails

Bart

Team,

on the schematic of TUSB9261DEMO, page 19, there is FB4 filter, C54, C64 and resulting voltage USB2_1P1V; then also filter FB5, C62, C58, C59, C61 and voltage VDDA_1P8V.

What are these two voltages meant for?

Thanks!

over 6 years ago

0 Brian Zhou over 6 years ago

TI__Guru**** 158325 points

1P1V means 1.1v and 1P8V means 1.8v.

0 Bart over 6 years ago in reply to Brian Zhou

TI__Expert 6500 points

Hi Brian,

Can you explain what they are actually used/needed for?

0 Brian Zhou over 6 years ago in reply to Bart

TI__Guru**** 158325 points

1.1v is for VDD supply of 9261, 1.8v is for crystal

0 Bart over 6 years ago in reply to Brian Zhou

TI__Expert 6500 points

Hi Brian,

thanks. I clicked that it resolved the issue, but in fact would need more explanation - from the VDD_1P1V (1.1v) that is used for 9261 supply, the USB2_1P1V is derived (after filter) - what for?

Secondly, from the crystal supply (BOARD_1P8V) from U4, the VDDA_1P8V is derived (after filter) - what for?

0 Brian Zhou over 6 years ago in reply to Bart

TI__Guru**** 158325 points

FB is Ferret bead, all our design has it. Just to filter noise and EMI

0 Bart over 6 years ago in reply to Brian Zhou

TI__Expert 6500 points

Hi Brian,

this is not what I was asking about. I was asking why do we create USB2_1P1V and VDDA_1P8V voltage rails in this schematic, as they do not seem to have any further connections on the schematic.

Can you please check and advise on that?

Thanks.

0 Brian Zhou over 6 years ago in reply to Bart

TI__Guru**** 158325 points

are we look at same schematic?

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TUSB9261DEMO: USB2_1P1V and VDDA_1P8V voltage rails