JAJSUT1B June 2024 – November 2024 TUSB2E221
PRODMIX
USB 2.0 specification does not specify high-speed output differential swing VOD during disconnect without external load. Only chirp level and HS host disconnect threshold are specified. Specification implicitly assumes high-speed output differential swing VOD will double during disconnect. However, the high-speed output differential swing during disconnect depends on the USB 2.0 TX output swing and pre-emphasis setting, as the common-mode voltage increase can saturate the output swing level and may not double.
The high-speed host disconnect threshold can be adjusted to provide the most margin to avoid false disconnect as well as failure to detect a disconnect. See Table 8-3.
| USB HS TX Pre-Emphasis | ||||||
|---|---|---|---|---|---|---|
| USB HS TX Amplitude (Vp-p) | 0.5dB (0h) | 0.9dB (1h) | 1.2dB (2h) | 1.7dB (3h) | 2.1dB (4h) | 2.5dB (5h) |
| 740mV (0h ) | 545mV (1h) | 545mV (1h) | 545mV (1h) | 545mV (1h) | 545mV (1h) | 545mV (1h) |
| 760mV (1h ) | 565mV (2h) | 565mV (2h) | 565mV (2h) | 565mV (2h) | 565mV (2h) | 565mV (2h) |
| 780mV (2h ) | 585mV (3h) | 585mV (3h) | 585mV (3h) | 585mV (3h) | 585mV (3h) | 585mV (3h) |
| 800mV (3h ) | 585mV (3h) | 585mV (3h) | 585mV (3h) | 585mV (3h) | 585mV (3h) | 585mV (3h) |
| 820mV (4h ) | 605mV (4h) | 605mV (4h) | 605mV (4h) | 605mV (4h) | 605mV (4h) | 605mV (4h) |
| 840mV (5h ) | 625mV (5h) | 625mV (5h) | 625mV (5h) | 625mV (5h) | 625mV (5h) | 625mV (5h) |
| 860mV (6h ) | 645mV (6h) | 645mV (6h) | 645mV (6h) | 645mV (6h) | 625mV (5h) | 625mV (5h) |
| 880mV (7h ) | 645mV (6h) | 645mV (6h) | 645mV (6h) | 645mV (6h) | 645mV (6h) | 645mV (6h) |
| 900mV (8h ) | 665mV (7h) | 665mV (7h) | 665mV (7h) | 665mV (7h) | 665mV (7h) | 645mV (6h) |
| 920mV (9h ) | 685mV (8h) | 685mV (8h) | 685mV (8h) | 665mV (7h) | 665mV (7h) | 665mV (7h) |
| 940mV (Ah ) | 685mV (8h) | 685mV (8h) | 685mV (8h) | 685mV (8h) | 665mV (7h) | 665mV (7h) |
| 960mV (Bh ) | 705mV (9h) | 705mV (9h) | 705mV (9h) | 685mV (8h) | 685mV (8h) | 665mV (7h) |
| 980mV (Ch ) | 725mV (Ah) | 705mV (9h) | 705mV (9h) | 705mV (9h) | 685mV (8h) | 685mV (8h) |
| 1000mV (Dh ) | 725mV (Ah) | 725mV (Ah) | 705mV (9h) | 705mV (9h) | 685mV (8h) | 685mV (8h) |
| 1020mV (Eh ) | 725mV (Ah) | 725mV (Ah) | 725mV (Ah) | 705mV (9h) | 705mV (9h) | 685mV (8h) |
| 1040mV (Fh ) | 745mV (Bh) | 725mV (Ah) | 725mV (Ah) | 705mV (9h) | 705mV (9h) | 685mV (8h) |