ISOUSB111: USB Communication Failure - Noise

bhupendra suthar

Intellectual 505 points

Part Number: ISOUSB111
Other Parts Discussed in Thread: SN6507

Tool/software:

TI Team,

Good Day !

Our industrial control board has USB 2.0 Interface , FULL speed ( 12 Mbps ) HID Device.

Currently , Between MCU and USB Connector , EMI filter and TVS Diode is Used. 90 Ohm Differential Impedance achieved using 4 layer PCB Layout.

During Normal scenario , communication works fine between PC and Board.

Issue is : when we have Industrial premises , due to noise we are facing communication Failure and Data Corrupt issue.

Can ISOUSB111 is best suits to resolve this ? or you can suggest any other part as well.

2 months ago

0 Varun Kumar 2 months ago

TI__Expert 7385 points

Hi Bhupendra,

Thanks for reaching out.

The ISOUSB111 is an Isolated USB repeater and can definitely be used to improve USB Communication in a noisy environment by strengthening the USB Signals in between and also breaking any kind of Ground Loop that might be forming due to industrial noise environment.

You can evaluate the solution putting ISOUSB111 EVM in between PC and Board and see for any improvement which will also help you to root cause the noise injection source in system (Wire Harness vs something near the board itself)

Regards
Varun

0 bhupendra suthar 2 months ago in reply to Varun Kumar

Intellectual 505 points

Hello Varun,

We have used ADum3160 ( guessing Similar to ISOUSB111) Isolator to try out , as its low cost module was easily available.

Unfortunately , It did not work out at Full Speed. Enumeration was Failed.

For Low speed it worked.

Best Regards,

Bhupendra

0 Varun Kumar 2 months ago in reply to bhupendra suthar

TI__Expert 7385 points

Hi Bhupendra,

ISOUSB111 and ADuM3160 might be functionally similar but ISOUSB111 is based on completely different technology and is a completely different device internally which is much more Immune to external noise.

Since you already have the socket in place, please try replacing with ISOUSB111 and observe the improvement.

Regards
Varun

0 bhupendra suthar 2 months ago in reply to Varun Kumar

Intellectual 505 points

Thanks , Varun for the update.

We do not have socket on the board. We used Off-the-shelf Module as below :

https://www.amazon.in/Isolator-ADUM3160-Coupling-Protection-Industrial/dp/B088MBRQSV

you can suggest such module if available with : ISOUSB111

We will replicate your suggestion.

Best Regards,

Bhupendra

0 Varun Kumar 2 months ago in reply to bhupendra suthar

TI__Expert 7385 points

Hi Bhupendra,

Thanks for the inputs.

You can use ISOUSB111 EVM for easy and modular testing : https://www.ti.com/tool/ISOUSB111DWEVM

Regards
Varun

0 bhupendra suthar 2 months ago in reply to Varun Kumar

Intellectual 505 points

Thanks, Varun

We will buy it.

FYI, mostly we Found issue with places where earthing is not Good ( ~6.3 VAC) Or the PC System has Noisy SMPS.

Regards,

Bhupendra

0 bhupendra suthar 2 months ago in reply to Varun Kumar

Intellectual 505 points

Hello Varun,

Out of curiosity, Why do we need Specialised IC like ISOUSB111 to isolate USB communication ? Can not we use Normal High Speed Digital Isolator Instead ?

0 Varun Kumar 2 months ago in reply to bhupendra suthar

TI__Expert 7385 points

Hi Bhupendra,

Well there are many USB protocol and enumeration level details that gets taken care by an Isolated USB transceiver (ISOUSB111) which can not be communicated through Normal Digital Isolators.

Also, USB is a differential signal protocol and can not be interfaced with single ended IOs of Digital Isolators

Regards
Varun

0 bhupendra suthar 2 months ago in reply to Varun Kumar

Intellectual 505 points

Ok , varun

We thought ISOUSB111 is just Hardware level isolator , Not aware about enumeration Handling.

As per your suggestion , while using ISOUSB111DWEVM do we need to remove Pull-up (1k5) on D+ Line of Our MCU Board ? Our MCU ( 3.3V ) has Full speed Support Only.

Also , We are Using USB cable from PC ( 1.8 Mtr) with Ferrite attached Both side , would it attenuate the signal reaching to ISOUSB111 ?

0 Varun Kumar 2 months ago in reply to bhupendra suthar

TI__Expert 7385 points

Hi Bhupendra,

You can remove the external 1.5kohm Pull-up on MCU board. The ISOUSB does not need it.

No issues with your cable, Cables up to 5m are supported with ISOUSB and no issues with ferrite beads as well.

Regards
Varun

0 bhupendra suthar 2 months ago in reply to Varun Kumar

Intellectual 505 points

Hello Varun,

As per USB Specification , Pull-up resistor is to identify Full Speed Operation.

So, you mean ISOUSB has in built pull-up for Full Speed Operation ?

0 Varun Kumar 2 months ago in reply to bhupendra suthar

TI__Expert 7385 points

Hi Bhependra,

bhupendra suthar said:
So, you mean ISOUSB has in built pull-up for Full Speed Operation ?

Yes.

Regards
Varun

0 bhupendra suthar 2 months ago in reply to Varun Kumar

Intellectual 505 points

Thanks Varun,

Can you help me to understand PIN function of ISOUSB111 in my scenario ?

Our Setup is as follow :

USB Controller ( MCU 3.3V ) ---> Shielded USB Cable (1.8 mtr) --> ISOUSB111 Module ----> PC

Also , you can suggest which side better to put ISOUSB111 , Peripheral Side Or Host Side ?

Regards,

Bsuthar

0 Varun Kumar 2 months ago in reply to bhupendra suthar

TI__Expert 7385 points

Hi Bhupendra,

PIN(Pin12) needs to be HIGH for the Pull Up Detection on DD+/-.

For your application, since you're using the EVM board, short the R20 resistor and you should be good to go.

bhupendra suthar said:
Also , you can suggest which side better to put ISOUSB111 , Peripheral Side Or Host Side ?

To avoid any confusion, you can connect UD+/- to the Host Side and DD+/- to Peripheral Side.

Regards
Varun

0 bhupendra suthar 2 months ago in reply to Varun Kumar

Intellectual 505 points

Hello Varun,

Thank you for your continue support.

See attached Setup Image FYR. you can suggest any other changes required...

As you mentioned R20 Will be shorted.

Regards,

Bsuthar

0 Varun Kumar 2 months ago in reply to bhupendra suthar

TI__Expert 7385 points

Hi Bhupendra,

I don't have any comments on the above image as this was clear from beginning.

I believe instead of ISO211EVM you meant ISOUSB111EVM.

Regards
Varun

0 bhupendra suthar 2 months ago in reply to Varun Kumar

Intellectual 505 points

Hello Varun,

For Designing on PCB level with ISO111 should i start another ticket Or Continue with this Thread ?

0 Varun Kumar 2 months ago in reply to bhupendra suthar

TI__Expert 7385 points

Hi Bhupendra,

You can start a new thread for that, But I recommend to use our EVM Layout(in User Guide) as much as possible and then get it reviewed by us later on.

Since you're asking about PCB, should I safely assume that ISOUSB111 passed your industrial test scenario?

Regards
Varun

0 bhupendra suthar 2 months ago in reply to Varun Kumar

Intellectual 505 points

Hello Varun,

EVM is in custom and Delivered into 3-4 days.

Just want to start Parralley on design. Instead of Dc-DC Convertor from WE we may plan to use Other make Like Mornsun...

I believe not necessary to use same , Correcr ?

0 Varun Kumar 2 months ago in reply to bhupendra suthar

TI__Expert 7385 points

Hi Bhupendra,

Do keep us posted on the test results with EVM.

bhupendra suthar said:
I believe not necessary to use same , Correcr ?

Yes, As long as the voltage and current requirements are meant any converter can be used. FYI, we don't have a DC-DC converter on the EVM rather it is a transformer from WE driver by a different transformer driver IC.(SN6507)

You can create a new thread for any power supply related query using transformer driver with the exact part number.

Regards
Varun

0 bhupendra suthar 1 month ago in reply to Varun Kumar

Intellectual 505 points

Hello Varun,

We tested it at Our site , and Initial one day Trial was successful. Thanks for your suggestion.

Note : we have not shorted R20 Resistor. we used EVM as is.

For On-board design with ISOUSB111 , apart from EVM Reference design is there any other AppNote / e2e Thread you recommend to refer ? Considering Self-powered Board.

Regards,

Bhupendra

0 Varun Kumar 1 month ago in reply to bhupendra suthar

TI__Expert 7385 points

Hi Bhupendra,

Great to hear that.

bhupendra suthar said:
Note : we have not shorted R20 Resistor. we used EVM as is.

Yes, it will still work but it is safer to have it pulled high in a noisy environment to avoid any unwanted noise coupling on PIN.

Currently, the EVM reference design is the best that we have to offer as a reference design. You can refer the schematic pin connections in our datasheets as well. You can get the final schematic reviewed with us once you have it ready.

Regards
Varun

0 bhupendra suthar 1 month ago in reply to Varun Kumar

Intellectual 505 points

Hello Varun,

We found that EVM schematic is in Two layer. Not sure to achieve 90 Ohm Impedance with 2 layer design.

Should we go for 4 Layer ?

0 Varun Kumar 1 month ago in reply to bhupendra suthar

TI__Expert 7385 points

Hi Bhupendra,

How to achieve impedance matching on PCB is something which we can not recommend. This limitation is governed by PCB Manufacturers. Please Consult them for achieving your desired impedance on PCB and in the layers of your choice.

However, the ISOUSB operation will not be affected by number of layers on PCB as long as the 90ohm Diff Impedance is achieved on D+/D-.

Regards
Varun

+1 bhupendra suthar 28 days ago in reply to Varun Kumar

Intellectual 505 points

Okay , Varun
Thanks for your support. I am Closing this Thread.

For Design Review I will open New one.

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ISOUSB111: USB Communication Failure - Noise