Author Topic: Correct polarity of Rohm YFZ diode?  (Read 591 times)

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Offline Gandalf_SrTopic starter

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Correct polarity of Rohm YFZ diode?
« on: March 01, 2020, 11:59:41 am »
I created a footprint and component in Diptrace for the Rohm YFZVFHTR5.6B Zener diode but the 3D model that was linked from the Rohm web site for this part seems to contradict the drawings in the datasheet.

The 3D CAD .step file (to be fair, Rohm says it's from an outside source) shows that the cathode marking on the top of the device corresponds to the smaller of the 2 pads under the diode.  However, the annotated picture I show below gives my interpretation of the drawings which indicates that the cathode is the larger of the 2 pads on the underside of the diode; which one is right?

I can't order my PCB until I'm sure which way round it is although I strongly suspect that the cathode is the larger pad; I do have some parts on order but hoped maybe someone here could help.

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Offline Gandalf_SrTopic starter

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Re: Correct polarity of Rohm YFZ diode?
« Reply #1 on: March 08, 2020, 11:37:30 am »
Answering my own question.  The part arrived and my picture above is correct, the larger of the 2 pads is the cathode.  The 3D model shows a dot, which I assumed was intended as the cathode marker, on the top side of the device but it's at the anode end, i.e. it corresponds to the smaller of the 2 pads. So the 3D model is wrong.
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Offline Siwastaja

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Re: Correct polarity of Rohm YFZ diode?
« Reply #2 on: March 08, 2020, 01:56:43 pm »
Rule of thumb: in case of discrepancy, 3D models are almost always wrong. Their significance is still underestimated, and they are still treated as "entertainment" by the manufacturers, hence, creating the models is left for some summer trainee (if the model is available at all).
 

Offline Gandalf_SrTopic starter

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Re: Correct polarity of Rohm YFZ diode?
« Reply #3 on: March 08, 2020, 03:18:45 pm »
Rule of thumb: in case of discrepancy, 3D models are almost always wrong. Their significance is still underestimated, and they are still treated as "entertainment" by the manufacturers, hence, creating the models is left for some summer trainee (if the model is available at all).
Great comment, thanks :D
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