# Series Damping Resistor for Low-Speed USB

The USB 1.1 spec gives well-defined $V/I$ characteristics for full-speed output drivers, which can be used to find the series damping resistance, $R_S$. The low-speed output schematics also reference $R_S$, but it's not entirely clear if it's the same (since low-speed characteristics are typically less strict than full-speed). And while the spec states:

In the rest of the chapter, references to the buffer assume a buffer with the series impedance unless stated otherwise.

Does that mean it applies to both low-speed and full-speed, or just full-speed? If it's the latter case, then what's the valid range of $R_S$ for low-speed output drivers?