TPD4E1U06: ESD Protection for MIDI

Hi Hideki,

I would still go with a 2 channel device and put one on each MIDI port. It looks like the ports are on different sides of the board. This will cause high parasitic inductance if the traces are too long connecting the ports to the ESD device. You can read more about this here: https://www.ti.com/lit/an/slvaex9/slvaex9.pdf?ts=1624458902636&ref_url=https%253A%252F%252Fwww.ti.com%252Finterface%252Fcircuit-protection%252Fesd-protection-and-tvs-surge-diodes%252Ftechnical-documents.html 

Unidirectional devices usually offer better clamping if the signal does not go below ground during normal operation which seems to be the case for this application. However, we do have bidirectional diodes that might offer better specs than some unidirectional diodes like higher IEC 61000-4-2 rating or lower capacitance. 

You are correct on the Vrwm statement. You want the Vrwm of the ESD device to be as close to the normal operating voltage levels as possible. 

If you are using the 3.3 V signaling, I would recommend ESD122, and for the 5 V signaling, I would recommend TPD2E2U06. 

Let me know if you have any more questions on this. 

Regards,

Matt Smith