usb ESD protection in stm32f4discovery

[armindavatgaran]

Posted on June 09, 2015 at 13:42

Hello

The OTG side of the stm32f4discovery is ESD protected, but there isn't such protection in the STLINK side, why?How can we decide whether to put ESD protection IC or not? 

[Tesla DeLorean]

Posted on June 09, 2015 at 22:06

How can we decide whether to put ESD protection IC or not?

Are you going to sell it as a commercial product to the public, and provide technical support for it? Are people going to plug the USB connector in/out, or touch your board and it's connectors?If you can answer these questions you should know the answer to your own question. 

[armindavatgaran]

Posted on June 10, 2015 at 13:42

What is the difference between STLINK and USB-OTG sides of the stm32f4discovery, by considering the factors you mentioned?

[Tesla DeLorean]

Posted on June 10, 2015 at 15:27

I didn't design the F4-DISCO, but it's a $15 board, you break it, you throw it away and buy another. The costs to ship back and forth across the country exceed the value. All these things will work without protection, until they fail.

If you sell a $150 product you don't really want to deal with angry customers and returns of broken/damaged devices. You add circuitry to limit or mitigate damage. The OTG device might be externally powered? Different potentials? Printers that work via static discharge, or generate it as a result of paper movement?