• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 33 subscribers
  • Views 273 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TUSB212EVM: Led D1 HS EN not work

Andrei Zhukouski
Prodigy 20 points

Part Number: TUSB212EVM

Tool/software:

I used the HS detection circuit on transistor Q1 .

When the VREG signal 1.8V appears, the LED does not light up. The LED itself receives a voltage of 1.4V. At the same time, the LED should have a voltage of at least 2.0V. If you swap resistor R2 and LED D1, the indication starts to work normally.
Is this an error in the circuit?

  • 0
    TI__Mastermind 37350 points

    Hi Andrei,

    The EVM has VREG tied to this LED and not ENA_HS, which while it should still work in terms of functionality, may help indicate an issue. Can you measure pin 1 of J5, which is connected to BOOST/ENA_HS, and see what you see there when the device should be operating? If the output of that pin is high, then it may indicate that there is an issue with the connection of that LED.

    Thanks,

    Ryan

  • 0 in reply to Ryan Kitto
    Prodigy 20 points

    I don't have the EVM board itself, I replicated the schematic.


    When the USB2.0 device is connected, 3.3V appears on the BOOST/ENA_H pin, when disconnected - 0V.

    I clarify the question about the correctness of the LED connection.
    I have modeled the circuit. As an LED equivalent I took a 2.4V zener diode.

    You can see that the voltage does not reach the LED turn-on voltage

    If we swap the resistor and the LED, the voltage exceeds the LED turn-on voltage by 2 volts. The current will be limited by the resistor

  • +1 in reply to Andrei Zhukouski
    TI__Mastermind 37350 points

    Hi Andrei,

    This does appear like an issue with the circuit then, yes. However, overall, I would recommend sticking to the ENA_HS pin for indicating when the device is in high-speed mode or not. It is more consistent, and the pin is intended to be a status pin.

    Sorry about that issue.

    Thanks,

    Ryan

  • +1 in reply to Ryan Kitto
    Prodigy 20 points

    Hi Ryan,

    Thanks for the recommendations.