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I'm currently doing my first Project using custom PCBs. It's a CAN based system to control things around my house (lights, blinds, sound, etc.). I'm planning to use multiple STM32F103C6 (in Form of a Blue Pill development board) with an external PCB that has (depending on intended usage) the CAN transceiver(MAX3051ESA), led drivers, buttons, faders, etc.

Do I need an external ESD protection device (like PESD1CAN) when using the MAX3051ESA? The MAX3051ESA has a 12kV Human Body Model ESD Protection and the PESD1CAN has a ESD protection up to 23 kV.

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  • \$\begingroup\$ The question is, do you expect a lot of ESD striking to the CAN pins? Like will you be choosing the connectors so that you can directly poke the data pins, or otherwise be constantly plugging and unplugging the connectors? By choosing the connectors so that grounds always connect first and data pins last, there may be no ESD issues around your home. \$\endgroup\$
    – Justme
    Commented Mar 4 at 13:51
  • \$\begingroup\$ I'm currently planning to use WAGO 252-104 connectors, where every pin is connected at the same-ish time. These will be set up once and replugged only when replacing the hardware or updating the software. \$\endgroup\$
    – P Z
    Commented Mar 4 at 13:57
  • \$\begingroup\$ Then it depends on how the modules are powered. If they have separate floating power supplies, just protecting from ESD may not be enough. If they all have power supplies that offer a common ground potential, then everything should already be at equal potential. \$\endgroup\$
    – Justme
    Commented Mar 4 at 14:02
  • \$\begingroup\$ You need as much ESD protection as your environment requires. Human body model is for humans sticking their fingers onto CAN connectors and the like. But in case of industrial/automotive etc you might need higher protection yet, from other forms of transients. \$\endgroup\$
    – Lundin
    Commented Mar 4 at 14:12
  • \$\begingroup\$ External ESD protection device like the PESD1CAN is recommended for better protection against ESD events. \$\endgroup\$
    – liaifat85
    Commented Mar 4 at 19:54

2 Answers 2

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Maybe not, but if you're running a CAN bus all around you might want to have it.

The human body model may not be adequate compared to a real-world ESD strike from (say) a nearby lightning strike. Other standards are used. Suppliers of external ESD-protection devices are always happy to inform you of their raison dêtre,

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Regarding external ESD protection: it depends on your requirements. You don't mention them, so we can't answer that. Human body model is for humans sticking their fingers in some connector. There are other forms of transients though.

In very demanding environments (some automotive, aerospace, military etc) it is custom with external TVS on the CAN lines. For general industrial applications, it is probably a bit overkill. But it also depends on what the transceiver itself can handle.

Regarding the CAN transceiver you propose, it is old and shouldn't be used in new designs.

The quality of these parts can often be noted with how large a voltage span they can handle on the CANH/CANL pins. The MAX3051 specifies -7.5V to +12.5V absolute maximum. Compare this with a modern part such as MCP2562FD, which is rated at -58V to +58V DC voltage on the same pins, and transients of -150V to 100V. That's a huge difference!

ESD wise they are about the same, with MCP2562FD specifying +/-14kV on CAN lines and lower on other pins, whereas the Maxim part doesn't say which ones (all or just CAN lines?).

Why pay double the price for old, bad Maxim parts when you can get a modern part playing in a different league entirely, for half the price?

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