1
\$\begingroup\$

I am working on incorporating ESD protection for flash circuitry on ESP32 custom PCB board, and after initial research, ordered an ESD Array (CM1293A-04SO) from digikey with datasheet here

Attached in the circuit diagram below, showing

  • USB Rx, Tx, and Pin 0 connecting to 3 channels of the array, and
  • Handmarked "Flash_3.3V" netlabel connecting to Channel 3,4 via Blue Line and connecting to IC Power Source at pin 5 via Red Line.

My questions is regarding the power line (2 options drawn in red and blue), and I am wondering if the array can simulataneously power and protect the incoming power from USB line.

Circuit Diagram

I got this idea from another protection array RClamp7522T with datasheet link here. with similar electrical circuit ( but higher pricing, with lower capacitance, higher protection range for ESD, a shared zener diode, and no power source), where it shows on page 7, that IC can protect power circuit as well. Please see screenshot

for page 5 here.

\$\endgroup\$
2
  • \$\begingroup\$ I came across the post mentioned below where someone said ESD pulse can be handled by the bypass capacitors which I have in place. I guess, I need to build the circuit and test it out myself. electronics.stackexchange.com/questions/401699/… \$\endgroup\$
    – Amogh Jain
    Commented Jan 2, 2021 at 0:20
  • 1
    \$\begingroup\$ Yes, either will protect. \$\endgroup\$
    – DKNguyen
    Commented Jan 2, 2021 at 2:46

1 Answer 1

1
\$\begingroup\$

So I learned and answered my original Questions after some R&D :

ESD protection is different for

  • Digital I/O Lines
  • Power Lines

Digital IO Lines :

  • as they are usually one way Industry preference if for high preference for unidirectional TVS
  • Additionally CMOS inputs are VERY sensitive to negative spikes, and unidirectional TVS have IV characteristic curves where cutoff/forward bias for negative spike is MUCH less than Positive spike
  • Power Dissipation Requirement is low, order of milliWatts

Power Lines :

  • Require Large Power Dissipiation (watts)
  • Industry practise is to use bidirectional TVS's

The above IC being used and tested, and even thoough working, WILL not provide rectification for power, as it is rated ONLY for ~250milliWatts.

Going to replace :-

  1. Digitial IO Protection with : Applied-Power-AU3321D5_C393856 @ LCSC $0.03
  2. Power Line Protection with : MMBZ5V6ALT1 @ Digikey (0.10), and LCSC @ $0.03 with 40Watts sinking capability.
\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.