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TSU6721 MIC to VBUS question

daniel
Genius 5095 points
Other Parts Discussed in Thread: TSU6721

Hi,

We face an problem that the MIC voltage is not match with VBUS voltage.


We set register 0x13 = 0x4A, and measure MIC pin, the voltage is 1.7V. But the voltage of VBUS is 0.6V~0.2V, and would keep bounce.

If we add a 1M ohm on ID pin, the VBUS voltage will be 1.7 V.

Why?

Could we set register to get stable 1.7V?

Below are register dump, pic1 is VBUS unstable, pic2 is VBUS stable. The only difference is 0x02. Is this setting the root cause?

Thanks

  • 0
    Genius 5095 points
    Hi team,

    We use audio jack to achieve charger, USB and headphone function.

    We do not have ID pin to detect and automatic switching, we can only use manual switching.

    Can we floating the ID pin?

    We did some experiment:

    1. ID pin floating, and the MIC/VBUS switch would not switch by manual.

    2. We pull down 200K on ID pin, and MIC/VBUS can normal switch by manual.

    Is it necessary to pull down the ID pin if we only use manual control?

    Thanks
  • 0 in reply to daniel
    TI__Mastermind 45370 points

    Daniel,

    If you float the ID pin on the TSU6721 the device will read it as "no ID" as seen in the table below.  This will place all of the switches in high impedance. 

    Placing a 200k ohm pull down on the ID pin will configure the device for Type 1 charger with the USB switch ON and set ISET status pin.


    What are you trying to accomplish with the TSU6721?  The TSU6721 is a highly integrated device with a large set of features.  We have stand alone ICs that do all the functions inside the TSU6721 if you are not utilizing the entire TSU6721 feature set that may be more suitable for your needs.

    Thank you,

    Adam

  • 0 in reply to Adam Torma
    Genius 5095 points
    Dear Adam,

    Thanks for your reply,

    Please help to confirm, why can not control the switch by register 13h normally, if floating ID pin?
  • 0 in reply to daniel
    TI__Mastermind 45370 points

    Daniel,

    You are not able to manually control the switches in the TSU6721 until after a valid detection sequence has been run on the ID pin.   Since you float the ID pin on the TSU6721 the device will read it as "no ID" as seen in the table below and will not initiate a detection.  

    You could ground the ID pin which would configure the switches as an OTG port and then be able to manually configure the switches since you had a valid detection. 


    Am I correct, you are not using all the features of this IC?  Would a basic I2C controlled switch be a better solution? 


    Thank you,

    Adam

  • 0 in reply to Adam Torma
    Genius 5095 points
    Dear Adam,

    Many thanks.

    We use audio jack, so do not have ID pin to detect and automatic switching
    We use I2C manual control the switch.