identification
Trying to debug a broken circuit board and the component circled in red seems to be key to understanding the behavior. I've scoured the internet as best I could, but cannot find any reference to anything even starting with EJ
I searched:
https://www.sphere.bc.ca/download/smd-codebook.pdf
https://www.digikey.jp/en/pdf/m/micro-commercial-co/mcc-smd-marking-codes
https://alltransistors.com/smd-search.php?search=EJV
Any tips for where to look next?
Going by look and reference designator (F20, mirrored in the OP’s image), it seems to be fuse. One of the fuse from Bourns can match it. Further confirmation can be made by inspecting the resistance of it. looking at the copper trace width, it looks like power plane. See the image below:
Datasheet: http://www.bourns.com/docs/Product-Datasheets/sf0603f.pdf
It is most likely a Schottky barrier diode to accelerate the turn-on/turn-off speed of the gate of the PMOS. From the information given, it is hard to point on what consumer it is actually from. We would need more details for this. But what you could do is unsoldered the part and perform a few test to confirm my hypothesis.
Apply a small voltage (0.5V) and put a small load on either pin on the side with two pins. See if it conducts. Apply a larger voltage (2-5V) and look at the voltage drop of the diode (if it is indeed a diode).
You could also put the part on a curve tracer to see the characteristics like the breakdown voltage and the forward voltage. It is either two Schottky barrier diodes in parallel or a single one as shown below:
For a PMOS device, I would expect the diode to be arrange like the middle picture. Either single or double.
Best Answer
The best option I can find would be the Nexperia PMV33UPE, a P-Channel Power MOSFET with marking
EJ%.The
%in the marking is a placeholder for a manufacturing code, which I cannot find any further details on. It could conceivably be multiple characters, perhaps including date code information.The pin-out seems to make sense, in both cases the gate is connected to the skinny trace in your image, and the source/drain are connected to fat traces. In the case of the lower right, the source connectes to C68 and a possible power plane. The drain connects to an inductor, along with the cathode of a diode (whose anode is GND). This would be the classic topology of a Buck converter, so would make sense for a PMOS with this pinout to be used.