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ESD701-Q1: Designing with ESD701-Q1

Sv
Intellectual 695 points

Part Number: ESD701-Q1

Hello Team,

We are planning to use the ESD diodes ESD701-Q1 in one of our PCBs.
We have a connector on our PCB where some analog and digital signals are coming.
The analog voltage can span from -24V to +24V and the digital signals can be from 0V to 12V.

Can you please clarify the following doubts we are having?.

1). For analog signals spaning from -24V to +24V, is ESD701-Q1 a good choice?. And if it can be used, do we need to connect the Pin 2 (or Pin 1) to GND or -24V?.

2). These analog and digital signals are coming from another board. So do we need to connect ESD diode in both PCBs?.

3). The device shall have compliance to EN 61000-4-2.

4). The final product will have a metallic enclosure. So i belive it is better to connect the ESD diodes to the chassis GND (metallic enclosure). Please correct me if I am wrong.

5). We have isolated power in the design. And we have ESD diodes in both isolated and non isolated sides. Is there any probelm if we connect ESD diodes from both isolated and non isolated sides to same GND or Chassis GND.

Looking for your reply.

 

 

 

 

 

 

 

 

  • 0
    TI__Expert 5900 points

    Hi Sv,

    1) We usually leave some margin for the operating voltage condition to the VRWM of the diode we are using. I would recommend using a diode with a higher VRWM. Remember to check the voltage absolute maximum ratings of the pins you are protecting. ESD701-Q1 would clamp at 42V so that means that the abs max rating of the pin you are protecting should be 42V or higher. Connect either pin to your signal and the other pin to ground. 

    2) You should put the ESD diode on the pin you are trying to protect. Wherever the connection from board 1 to board 2 is, that's where it should be. A typical recommendation is to place the diode as close to the ESD source or connector as possible and place the portected IC much further from the diode than the diode is to the connector. Here is a good app note that explains it well. Link

    3) Our devices have different IEC 61000-4-2 V(ESD) Ratings. You will find this close to the top of our datasheets. See picture below. EN 61000-4-2 should be the same as IEC 61000-4-2.

    4) Read 2.4 Section (Optimizing Ground Schemes for ESD) of the link I provided in answer 2. It provides a very detailed explanation on this.

    5) I would recommend to connect both ESD diodes to Chassis GND.

    Let me know if you need anything else.

    Best,

    Bryan

  • +1 in reply to Bryan Rodriguez de San Miguel
    Intellectual 695 points

    Hello Team,
    Thank you for your reply.

    1). Understood

    2). Ok

    3). According to the document (link), it is advisable to connect the ESD didoes to the chassis GND.

    4). Ok. We believe it will not have any impact on isolation of the device. Please correct me if I am wrong.

  • +1 in reply to Sv
    TI__Expert 5900 points

    If you share your schematic, I can provide a more confident response to question 4.

    Let me know if you need anything else.

    Best,

    Bryan