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H723V + HS ULPI possible damage

Ultrawipf
Associate II

I am currently working on a H723 based HS USB device with external USB PHY (USB3320,USB3340,USB3300 tested).

While testing i have noticed that seemingly randomly between debug/flash cycles HS USB stops working with usually no activity on the bus but the HAL Phy setup usually still succeeds enabling the PHY but leading to an unknown device for the host.

After replacing the H7 everything works again indicating some internal damage. This has happened several times on different revisions each with other protection attempts already so i can rule out a random bad or damaged chip.

The closest matching report is this post hinting at possibly the weirdly unprotected analog switched PC2_C and PC3_C pins which are also present and used for DIR and NXT on the H723V.

There has never been activity on any ULPI pins coming from the STM after the initial HAL PHY setup with these damaged parts so damage within or behind the analog switch seems plausible that it does not see the NXT/DIR signals but could be something else. Once the Bus was stuck in a weird state with a high frequency signal only on the DP pin and NXT (ULPI was fine. Replacing H7 fixed it).

After this damage the internal USB still works.
DFU works and when reflashing to use the internal port instead of the HS ULPI was also successful. It seems to mostly affect the HS ULPI interface.

 

The debugger is an STlink v3 with the isolator addon. All external pins (and the _C and debug pins in one revision to be extra sure) are protected with clamping diodes.
The analog supply comes from the same 3.3V regulator as the main supply and USB phy supply. VREF+ is connected to VDDA and vrefbuf disabled. All analog inputs are connected to opamp buffers also powered by this same 3.3V supply and should not see any significant voltage spikes.

There are high power components on the same board but no damage or glitches have been observed during operation. The damage does likely occurs in the startup phase as it was never seen during operation and only after reflashing the chip.
Trying to reproduce possible voltage spikes during the reset state and capturing signals on possibly sensitive pins and supplies with a scope yielded no result yet.

 

So i would be very glad about any hint that might point me to a possible cause of these defects.
If there are any specific pins, startup conditions or anything where the chip is more vulnerable that might occur in such a configuration.

1 ACCEPTED SOLUTION

Accepted Solutions
FBL
ST Employee

Hi @Ultrawipf 

I suggest you open an OLS ticket or contact your local FAE to follow the steps in this case. Note that _C pins have current limitation (1mA). 

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

View solution in original post

4 REPLIES 4
FBL
ST Employee

Hi @Ultrawipf 

 


@Ultrawipf wrote:

The closest matching report is this post hinting at possibly the weirdly unprotected analog switched PC2_C and PC3_C pins which are also present and used for DIR and NXT on the H723V.


Did you check you're using the right pins for the ULPI interface on the H723?

FBL_1-1722339089904.png

The issue likely arises only during startup, not during operation, and potentially is related to your SW configuration.

 

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

Yes i am quite sure the pinout is correct as on the LQFP100 H723VG only the _C pins are available and it is generally working fine.

It does seem like damage happens during startup/programming only.

I did not capture any signal glitches and the connected USB3340/3320 is using 3.3V levels powered by the same LDO as the H723. DVDD, AVDD and USB PHY should always be present together so the possible cause is still unknown to me.

To be sure in the latest version i added inline resistors for these pins in case they somehow sink excessive currents in these situations if it even has anything to do with this issue or if it is possibly caused by something else in the analog domain.

FBL
ST Employee

Hi @Ultrawipf 

I suggest you open an OLS ticket or contact your local FAE to follow the steps in this case. Note that _C pins have current limitation (1mA). 

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

https://www.st.com/content/st_com/en/support/support-home.html

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