Texas Instruments Errata SLLZ053 - October 2006 TUSB2036 Errata
Summary
This errata document addresses a speed detection issue in the TUSB2036 USB hub controller and related TUSB2046B/TUSB2077A devices. The issue involves premature speed sampling at the first VIH crossing rather than after the specified 100ms debounce interval, potentially causing false low-speed detection with newer USB devices. Texas Instruments provides a software workaround involving CLEAR_PORT_FEATURE followed by RESET_PORT commands. No silicon fix is planned. Target users are embedded systems engineers, USB device developers, and firmware programmers integrating these TI USB hub controllers who need to implement the documented workaround for reliable device enumeration.
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Errata
SLLZ053–October
TUSB2036 Errata
Parts Affected
TUSB2036SLLS372B, TUSB2046BSLLS413B, and TUSB2077ASLLS414A
1.1 Symptom
TI has found that the TUSB2036 (also TUSB2046B and TUSB2077A) has slight violation in the
manner that it determines the intended speed of an attached downstream device.
1.2 Description
By the intent of the USB specification (shown in Figure 7-19), the speed should be determined by
sampling the DP or DM line following 100ms debounce interval after either signal (DP or DM) first
crosses the VIH threshold. The TUSB2036 (TUSB2046B, TUSB2077A) 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 TUSB2036 (TUSB2046B, TUSB2077A). Note that this device is
used extensively in the USB1.1 Goldtree suite, and this issue was never revealed, further pointing to the
fact that some newer devices have less control on DM than previous devices, although this is allowed by
the USB specification. TI has no planned fix in the pipeline, but wants users to be aware of this issue,
which can easily be avoided by guaranteeing that DP be asserted high before DM. In the event that
false low speed detection is observed, the situation can be resolved by performing
CLEAR_PORT_FEATURE(PORT_ENABLE) followed by RESET_PORT in the software driver,
assuming both DP and DM are now stable.
SLLZ053–October TUSB2036 Errata
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Page Summary Contents For Texas Instruments Errata SLLZ053 - October 2006 TUSB2036 Errata
Manual Details
| Brand | Texas Instruments |
|---|---|
| Pages | 2 |
| File Size | 19.85 KB |
| Published | June 16, 2026 |
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Frequently Asked Questions
What's wrong with the TUSB2036 hub?
It samples speed incorrectly, potentially misdetecting newer devices as low-speed.
Which specific chip revisions are affected?
TUSB2036SLLS372B, TUSB2046BSLLS413B, and TUSB2077ASLLS414A.
How can I fix false low-speed detection?
Perform a CLEAR_PORT_FEATURE(PORT_ENABLE) followed by a RESET_PORT in the driver.
Will Texas Instruments issue a hardware fix?
No, TI has no planned fix in the pipeline.
How can I prevent the speed detection issue?
Guarantee that DP is asserted high before DM in your system design.