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DS90UB935-Q1: request for troubleshooting/ layout check

user6294514
Prodigy 80 points
Part Number: DS90UB935-Q1
Other Parts Discussed in Thread: ALP, USB2ANY

Hello, I've designed system utilising DS90UB935-Q1 and DS90UB936 deserializer. PoC is built with reference parts. Due to size challenges on the serialiser side coax (RG-316) is directly soldered to PCB. On the receiver side we are using SMA. Transmission line was evaluated with VNA (twice: in our lab and in external laboratory specialised with RF measurement). There were no issues found (operating margins are probably safe).
Serialiser is receiving single data pair MIPI CSI-2 signal from sensor we have interfaced directly with receiver chip before going with SerDes solution. REFCLK on the deserialiser was chosen 24MHz 1.8V free-running oscillator with filtered supply and 33Ω serial resistor on clock line. On the receiver side there is also single MIPI lane to receiver chip. Coax is AC coupled with 100nF 0201 chip capacitors (size constraint, again)

There are some issues. While I can configure remote I²C slaves without any issues (confirmed with logic analyzer) I do have framedrops due to receiver losing lock. I can provide Altium project for review and also provide measurements, however now limited due to test hardware failures.

  • 0
    TI__Expert 5480 points

    Hello, 

    Are you powering the 935 using a PoC network or do you have an independent power supply? Do you always have lock drop or only when you send video data? Since you did s-parameter measurements, how did you verify they were ok? Were you send channel specs from one of our engineers?

    Thanks, 

    Sally 

  • 0 in reply to Sally Cheung95
    Prodigy 80 points

    Hello, 935 is powered with PoC network at the moment (I can also try independent power supply, it is not a problem, W will evaluate it). Insertion and return loss were acquired from 936 datasheet. Lock loss  is present (as a small glitch or glitch series) even in standalone BIST mode (without receiver circuit and with sensor in idle). Lock loss is less frequent with limited AEQ max value (F→7). Should I check lower capacity of coupling capacitors?

    [EDIT]
    I've bypassed power supply to serialiser, now situation seems to be exactly the same - LOCK is unstable, there are around 1.2s of lock condition and then I got burst of glitches for around 0.3s 

  • 0 in reply to user6294514
    TI__Expert 5480 points

    Hello, 

    Can you try independently powering and see if the lock drop still persists? Also, when you check the s-parameters, did you mean table 227? This is just for the PCB traces. Can you trying running MAP in the ALP GUI for the 936? You will want to optimize based on how your MAP look like like. https://www.ti.com/lit/an/snla301/snla301.pdf?ts=1595861418417&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FDS90UB954-Q1

    1. Run MAP in ALP. Let the scan start at 0, RX0 selected, and Final Regr Reset should be checked.

    1. Get the green/red bars filled
    2. Digital reset. 0x01 = 0x02
    3. Program min/max EQ (0 – 14) 0xD5 = 0xE0     (we recommend you leave EQ max at 14 to account for cable aging in which you will need EQ.)
    4. Program min/max Sfilter  0x41 = 0x__
    5. Enable Adaptive EQ. 0xD4 = 0x01  
    6. AEQ error control checks all errors (clk errors, packet encoding errors, parity errors). Enable sfilter adaption with AEQ. 0x42 = 71
    7. Restart AEQ. 0xD2[3] =1

     

     

  • 0 in reply to Sally Cheung95
    Prodigy 80 points

    Hello,

    Unfortunately, we do not have required hardware to start analysis with ALP. However, there is python script for MAP in ALP, which we will try to port to target CPU and then evaluate AEQ/SP settings and contact you later.

  • 0 in reply to Sally Cheung95
    Prodigy 80 points

    So we have ordered USB2ANY and it finally arrived. But the very moment I plugged it into PC and started ALP - I had firmware update request; of course, as always with all TI tools - it failed. And yes, LED is lit, but I already tried all methods described. And for your info - Win7 is not an option, got Win10 as most of companies these days (maybe except TI).

  • 0 in reply to user6294514
    TI__Expert 5480 points

    In the USB2ANY app, you can update the firmware before you try to run ALP.  Did you try that yet?