OMAP L138 USB 1.1

Inderjit Bains

Other Parts Discussed in Thread: OMAP-L138

Does the USB 1.1 port on the L138 require 24.9 series resistors and 15K pulldowns? The Logic PD schematic has them, but there is no mention of them in any datasheet for the L138. Also, most USB 1.1 implementation have 47pF to ground at the connector, but these are not present in the Logic PD schematic nor are the mentioned in the schematic. Are the caps required?

over 15 years ago

0 jc-ti over 15 years ago

TI__Mastermind 27585 points

Inderjit,

Which schematic revision are you referencing? I do not see the USB1 resistors and pulldowns in the latest Logic schematic. Can you include the page number and component designations?

-Jeff

0 Inderjit Bains over 15 years ago in reply to jc-ti

Expert 2745 points

Logic PD OMAP-L138 SOM-M1 Rev 3 Sheet 3. If this isn't the latest schematic let me know.

0 tlee over 15 years ago in reply to Inderjit Bains

TI__Guru 62975 points

Inderjit,

The 15k pull-down resistors are included inside the USB1.1 PHY so they are not needed. Series resistors are not explicitly needed, but the layout needs to meet USB spec impedance requirements.

-Tommy

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OMAP L138 USB 1.1