Wake up issue of SN65LVPE512RGER

Siddharth Chowdhuri

Other Parts Discussed in Thread: TUSB501, TUSB551

In our design, the re-driver “SN65LVPE512RGER” is used both on transmit (host) and receive (device) side. However we are using N/W protocol (Xlinix Aurora) over USB3 physical medium along with this re-driver. Please refer to the block diagram below.

In our system there some issues that has been observed -

This device has been always enabled with pull up to VCC on EN pin.
Both Host and device are always connected with USB3 Cable. The Device on power up goes into a RX Detect mode , the TX/RX go to HiZ and doesn’t come up until it find a Termination. As the same re- drivers are being used on both ends, both get into a RX Detect mode and there is no deterministic way to get link active during power up or while making a fresh connection. There are no reset or program controls to push the device into Active mode. Interestingly once they are out or RX Detect mode and are active they stay active.

Is there any deterministic way to use these devices on both end of the cable. The max cable length we will use is 15~20 feet.

Thanks

Siddharth

over 7 years ago

0 Moises Garcia over 7 years ago

TI__Mastermind 23815 points

Hi Siddharth,

Unfortunately there is no way to use this device in cascade, newer devices will fix this problem.
Another solution is to replace LVPE512 by two TUSB501/TUSB551.

Regards

0 Siddharth Chowdhuri over 7 years ago in reply to Moises Garcia

Prodigy 120 points

Hi,

Let us know when the newer device(s) are going to be available which will fix this problem.

Also planning to use the following configuration - The re-driver “SN65LVPE512RGER” is on transmit (host) side and two TUSB501/TUSB551 on device side (or vice-versa). If such cascading mechanism is used, is there any problem foreseen.

Thanks,
Siddharth

0 Moises Garcia over 7 years ago in reply to Siddharth Chowdhuri

TI__Mastermind 23815 points

Hi Siddhart,

There is no problem foreseen, however we haven't tested it.
I can run this test next week.

Regards

0 Siddharth Chowdhuri over 7 years ago in reply to Moises Garcia

Prodigy 120 points

Thanks for the update. It would be good if you can let us know the test results next week.

0 Siddharth Chowdhuri over 7 years ago in reply to Siddharth Chowdhuri

Prodigy 120 points

Currently I'm holding the design implementation.

0 Siddharth Chowdhuri over 7 years ago in reply to Siddharth Chowdhuri

Prodigy 120 points

It would be good if you can ship us the reference board for TUSB501. Could not get the buy option from the website.

0 Moises Garcia over 7 years ago in reply to Siddharth Chowdhuri

TI__Mastermind 23815 points

Hi Siddharth,

This device's EVM is not for sale, it would be better if you have a FAE to request it. Otherwise, I would need a business case and go through a bureaucratic process.

Regards

0 Moises Garcia over 7 years ago in reply to Moises Garcia

TI__Mastermind 23815 points

Hi Siddharth,

I have conducted a simple test:
USB 3.0 memory <-(plugged)-> TUSB501 EVM, <--(plug/unplug)-> LVPE512 EVM <--(plugged)---> USB3.0 Host
When, connecting the two EVMs to each other, the USB memory is detected as USB 3.0

Regards

0 Siddharth Chowdhuri over 7 years ago in reply to Moises Garcia

Prodigy 120 points

Hi,

Thanks for conducting the test. We also did the quick check by adding to TUSB501 on one of our board and it seems working till now.

Prior to this experiment, we tried to connect ~100 ohm resistor between the differential pair at the Rx/Tx side on our boards, but LVPE512 was unable to come to active mode form Rx detect mode. This means that the LVPE512 does not only look for termination. It would be good if you could help us understand how this device comes out from Rx detect mode.

Thanks & Regards,

Siddharth

0 Siddharth Chowdhuri over 7 years ago in reply to Moises Garcia

Prodigy 120 points

Hi,

Can TUSB501 be used as a simple CML buffer or does it require USB protocol for operation.

Thanks & Regards,

Siddharth

0 Moises Garcia over 7 years ago in reply to Siddharth Chowdhuri

TI__Mastermind 23815 points

Hi Siddharth,

I'm looking for this information, I'll come back when I have an answer.

Regards

0 Moises Garcia over 7 years ago in reply to Moises Garcia

TI__Mastermind 23815 points

Hi Siddharth,

Could you try placing 50ohm resistor to GND in each Tx pin?

TUSB501 can be used as a general purpose redriver, but it is optimized for USB.

Regards

0 Siddharth Chowdhuri over 7 years ago in reply to Moises Garcia

Prodigy 120 points

Hi,

Thanks for confirming that TUSB501 can be used for general purpose re-driver.

Regarding the 50 ohm resistor to GND on Tx pin, there are few queries -

1. In LVPE512, these termination will be placed at Tx pin which will be in parallel to the internal Tx termination. Please confirm the same.

2. Typically the USB receiver SS signals have differential termination (between p & n ) for ex - there's internal differential termination in the receive pin of TUSB501. If this is the case then why does

a. LVPE512 wake up with TUSB501 connected at the other end

b. How will the single ended termination - 50 ohm to GND help.

Regards,

Siddharth

0 Moises Garcia over 7 years ago in reply to Siddharth Chowdhuri

TI__Mastermind 23815 points

Hi Siddharth,

I have confirmed the RX_TERM values should be from 18ohms to 30ohms, common mode(50 ohms should work too).

Yes they will connect in parallel with any internal resistor to LVPE512 connected to GND.

Besides, this resistors are for rx.detect, the devices have differential impedance too, you can review this values in TUSB501 datasheet page 5, or directly on USB specification section: Receiver Detection.

May I ask why you are trying to activate LVPE512 using discrete resistors?

Regards

Interface

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Wake up issue of SN65LVPE512RGER