Can anyone please help me to find what SMD component this is?

It is connected to 24 VDC on one side side (positive) and the other side to negative.


  • 4
    \$\begingroup\$ Possibly a TVS diode used as a spike quencher. \$\endgroup\$
    – Andy aka
    Commented Nov 16, 2022 at 21:03
  • 3
    \$\begingroup\$ The logo is Littelfuse so it's probably a TVS. Maybe you can measure the dimensions. \$\endgroup\$ Commented Nov 16, 2022 at 21:35

1 Answer 1


Marking DFM could be a SMLJ33CA (Micro commercial components corp) from a google search.

Looking up SMLJ33CA at www.littelfuse.com under Competitor Cross Reference, several candidates are shown. Looking through them, of course the last one shows a match. Marking DFM is Littelfuse model SMDJ33CA-HR.

This is a 33 Volt TVS or Transient Voltage Suppressor. These are like Zener diodes, in that once a certain threshold voltage is reached, they start to conduct. The net effect is that they clamp a voltage surge and prevent it from getting much higher.

These are commonly used on the power inputs of devices to prevent damage from over-voltage stress.

  • \$\begingroup\$ Good answer and good research \$\endgroup\$
    – Voltage Spike
    Commented Nov 16, 2022 at 23:06
  • \$\begingroup\$ Thank you rdtsc \$\endgroup\$ Commented Nov 17, 2022 at 21:49

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