Texas Instruments TUSB2046B Manuals

This document describes the features and characteristics of the RHB PACKAGE (TOP VIEW) VF PACKAGE (TOP VIEW) TUSB2046B TUSB2046BI products, including compliance with the USB specification, low power ASIC logic, integrated USB transceivers, support for one upstream port and four downstream ports, support for full-speed and low-speed operations, support for suspend and resume operations, support for programmable vendor ID and product ID, etc.

The TUSB2046B is a 3.3V CMOS hub device that provides a full-speed hub function compliant with the USB specification, with an optional serial EEPROM interface. It has various features, such as full compliance with the USB specification, integrated USB transceivers, state machine implementation without firmware programming, one upstream port and four downstream ports, support for full-speed and low-speed operations, etc.

This document mentions that TI's TUSB2046B, TUSB2077A and TUSB2036 chips have a small problem in determining the intended speed of an attached downstream device. According to the USB specification, the speed should be determined by sampling the DP or DM line following a 100ms debounce interval after either signal (DP or DM) first crosses the VIH threshold. The TUSB2046B (TUSB2077A, TUSB2036) actually samples the speed at the first VIH crossing and latches this value. This issue has only been observed recently with newer devices that either drive DM high or show excessive ringing during the initial connection, hence causing the speed detection to be seen as low speed by the TUSB2046B (TUSB2077A, TUSB2036).