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TPS65950: TPS65950 VBus Error – OTG_HandleVbusError

user3434218
Intellectual 690 points

Part Number: TPS65950
Other Parts Discussed in Thread: AM3715,

Hi,

Issue: USB can not work,Probability is 50%.

  1. System: Customer use wince
  2. AM3715 + TPS65950
  3. Power input: VBAT from Lithium battery
  4. System print VBus Error – OTG_HandleVbusError to be implemented when start up.
  5. There is 50 pecent USB can be right use, Other 50 pecent is print below info:

“###### FALL to read ULPI Reg,Control =0x5

Attempt Recovery Procedure 1

Assign ULPI Signals to GPIO

.......

  • 0
    TI__Genius 10885 points
    Could you provide a few more details for this failure?

    The charge pump for the OTG can only supply 100mA, could this be related to the 50%?

    This thread also solved a similar issue by debugging the CPOUT rail: e2e.ti.com/.../202852

    Best Regards,
    Rick S.
  • 0 in reply to Richard Solarski
    Intellectual 690 points
    We get the error info message when system boot,There have no peripheral use OTG charge pump.
  • 0 in reply to user3434218
    TI__Genius 17380 points
    Hello,

    Do you enable the OTG charge pump in your boot software? Or is there any possibility of your device thinking that it is an A type rather than B type USB connection?
  • 0 in reply to Kevin LaRosa
    Intellectual 690 points
    New status is :
    1.It's right work if power supply is 3.6V, Error at 3.8V power supply.
    2.If VIO connect to 2.8V can work right.
    3.When system start up, System print ULPI read error.
  • 0 in reply to user3434218
    Intellectual 690 points
    New Layout change （VMMC2.IN & VMMC1.IN & VAUX4.IN & VBAT.USB & VDAC.IN & VAUX12S.IN & VPLLA3R.IN & VINT.IN） from VBAT to 3.3V voltage can solve this issue，We checked spec & errata，These LDO input can connect to VBAT，Please explain it，Thanks！
  • 0 in reply to user3434218
    TI__Genius 17380 points
    Hello,

    There are many reasons a particular design can have issues. Changing input supplies for LDOs can have several impacts. First would be that reducing the VIN voltage should reduce the power consumption of the system. Perhaps the battery was not capable of supplying sufficient power for the system and switching to 3.3V supply reduced the load enough to work. Alternatively, perhaps the battery voltage was noisy due to other loads and was injecting into the LDOs if the input capacitor was either not sufficiently large or was too far from the input pin to sufficiently filter it out. Changing the input to the LDOs can also reduce thermal loads, though the problem description didn't seem to indicate this was an issue. You can continue to debug if you are interested in understanding the root cause by isolating individual pins and trying to see which was effected. VBAT.USB seems the most likely given the symptoms.