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Are there any implications to the signaling quality with the addition of the 1-MW leaking resistors on the PDIUSBD12 demonstration board?

April 26, 2017addition demonstration implications leaking pdiusbd12 quality resistors signaling

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Are there any implications to the signaling quality with the addition of the 1-MW leaking resistors on the PDIUSBD12 demonstration board?

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All the signals on the physical layer of USB are designed to be single-end terminated. At any one time, there can only be a transmitter and a receiver. The transmitter, or the driver, is required to have output impedance of between 28 W and 44 W. At the receiving end, the receiver must present an input impedance of > 300KW (exclusive of termination). When the PDIUSBD12 is in the driving state, the output impedance is between 29W and 44W. The effective impedance inclusive of the parallel pull-up at D+ of 1.5KW and the parallel pull-down at D+/D- of 1 MW does not vary that much with the driving impedance. During the receiving state, the total impedance is >300 KW even with the 1 MW leakage resistor present.