USB 2.0 and ESD

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ilaible
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First reply posted First question asked Welcome!

is it possible to protect an USB HUB 


so even if there are every second an ESD Peak 4kV

to GND or the Shield of the cable to communicate without interruption

with 12mbits fullspeed.

 

Is there a driver or protokoll available which granty, that no protocol will be lost?

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MallikaK_22
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50 likes received 750 replies posted 250 solutions authored

Hi,

I don't think there is any such defined protocol that will resend data in case of failure. Moreover, the effects of ESD damage are not uniform or defined across all devices. The best possible solution is to use TVS diodes for protecting the D+/D- lines. In the KBA mentioned above, the TVS diode has been tested against 4kv discharge. This should be enough for protecting the system and avoiding any data failures. Thus, the only best solution is to find the right value components that will solve ESD problems.

Also, It is not the hub that issues Port Pwr signal. Hub will monitor the DP/DM lines on the device and report the connection change status to host. Host is the one that will issue the Port Pwr signal to the port again based on the status change.

Regards,

Mallika

 

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MallikaK_22
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50 likes received 750 replies posted 250 solutions authored

Hi,

It is recommended to add external ESD diodes on the USB D+ and D- lines for hub protection.

Kindly refer to the following KBA: https://community.cypress.com/t5/Knowledge-Base-Articles/ESD-Protection-on-the-D-D-Lines-in-CY7C6562... 

Regards,

Mallika

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ilaible
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First reply posted First question asked Welcome!

thanks for the Answer, but the question is a little bit different:  We have the TVS ESD USB Diodes in use.

during I have an ESD contact Impuls +/- 4KV at my Device  direct to one of the metall ethernet ports an the decoupling Plate (so also somewhere between GND/Vcc/D+/D-) the communication signal of the USB will be bad.

a)  is there any mechanismus at USB , that a bad protocoll / bytes / bit will be automaticly resend?

b)  which max Signal level on the Signal at D+ D- is allowed, so the USB Tranceiver will still be detect the protocoll correct?

c)   when will an USB Hub make a "renumbering" or/and disconnect the PrtPWR Signal to the next USB Device and reconnect?

d)  how many bits/bytes could be disturbed, without reconnect the USB Hub? 

 

Thanks for your answer

 

Ingo

 

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MallikaK_22
Moderator
Moderator
Moderator
50 likes received 750 replies posted 250 solutions authored

Hi,

I don't think there is any such defined protocol that will resend data in case of failure. Moreover, the effects of ESD damage are not uniform or defined across all devices. The best possible solution is to use TVS diodes for protecting the D+/D- lines. In the KBA mentioned above, the TVS diode has been tested against 4kv discharge. This should be enough for protecting the system and avoiding any data failures. Thus, the only best solution is to find the right value components that will solve ESD problems.

Also, It is not the hub that issues Port Pwr signal. Hub will monitor the DP/DM lines on the device and report the connection change status to host. Host is the one that will issue the Port Pwr signal to the port again based on the status change.

Regards,

Mallika

 

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