USB Signal Strength

Srinivas Marakala1

Other Parts Discussed in Thread: TPS65930, DM3730

Hi,

We have DM3730 based custom platform and it has TPS65930 PMIC chip which also has OTG Phy. We are seeing low SUB signal strength when we try to do compliance tests on USB OTG port. Is there any setting in TPS65930 Phy or OAMP to increase the USB data signal stregth? I found similar settings with SMSC 3320 Phy.

Thanks,

Srinivas

over 12 years ago

0 Cvetolin Shulev-XID over 12 years ago

TI__Guru 65405 points

Hi Srinivas,

Could you share the values of the signal strength which you are measure on the USB OTG port when using TPS65930 to check whether are these normal values or there is some problem.

Tsvetolin Shulev

0 Srinivas Marakala1 over 12 years ago in reply to Cvetolin Shulev-XID

Intellectual 560 points

Hi Tsvetolin Shulev,

Thanks for the response. Sorry for the late response.

I asked our HW engineer for the signal capture. I am attaching the signal capture file. Is there any register to program the signal strength?6180.UsbOtgCapture.pdf

Thanks,

Srinivas

0 Cvetolin Shulev-XID over 12 years ago in reply to Srinivas Marakala1

TI__Guru 65405 points

Hi Srinivas,

After analyzing the Agilent's report - eye diagram I see that the signal edge is very closer to the border and only in part of the tests the signal edge crossing the borders. I can not obtain precise data about the slew rate is it in range according the TPS65930 Data manual but I recommend you to check the values of external coils and capacitors are they in recommended range.

http://www.ti.com/lit/ds/symlink/tps65930.pdf

Tsvetolin Shulev

0 Srinivas Marakala1 over 12 years ago in reply to Cvetolin Shulev-XID

Intellectual 560 points

Hi Tsvetolin Shulev,

Thanks for your quick response.

Our HW team is looking in to the electrical recommendations in datasheet. Can you please tell me if there is any way to increase the signal strength? For some Phy chipsets registers are available where in we can increase the USB signal strength.

Thanks,

Srinivas

0 Cvetolin Shulev-XID over 12 years ago in reply to Srinivas Marakala1

TI__Guru 65405 points

Hi Srinivas,

The physical parameters of the USB signal are managed by TPS65930. There is a E2E forum dedicated to TPS659xx PMU. Therefore I recommend you to ask you questions about electric part of USB at the link below:

http://e2e.ti.com/support/power_management/pmu/f/43.aspx

Tsvetolin Shulev

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USB Signal Strength