Hi, we chose the LiteOn LTP-757KR LED dot matrix for a design. Our assembly team is having trouble physically identifying pin 1 on the part because there isn’t an obvious indicator. Can we get some help with how to identify the pin orientation? Thanks!
The datasheet shows there should be a pin 1 marking in one of the corners. Since I am unable to confirm that with the photo we have online or from the manufacturer’s website, I have forwarded your request on to our product manager. I will update once we hear back from him, with a clearer answer on what the pin 1 indicator is.
Hi @gillian.lee
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Row 1, column 1, begin in upper left corner of the “+” plus marking highlighted in yellow per below, which will be on the front of the array:
Common Anode Rows, Common Cathode Columns
-Each of the 7 rows need positive voltage for the 5 LEDs
-Each of the 5 Columns need negative voltage for the 7 LEDs
Hi, our assembly team says that they don’t see any kind of marking on the component. I can ask them to double check, but is there another way to tell?
I think Lite-On, who normally have excellent datasheets, blew it on this one.
To get this run assembled, I’d use the part #/date code marking as a reference mark and assume that it is placed consistently throughout the batch of parts you currently have. Then I’d try out both possible orientations and note which way is correct. Hopefully it is at least consistent throughout the batch of parts you have.
Hopefully Lite-On will provide a better solution for future batches. They should have noted where the printing is located on the drawing view that shows the pin number cross mark.
Speculating, I bet they copied a data sheet for a part with a non-symmetrical display pattern and didn’t realize that with a symmetrical segment display there are two orientations that match the pin 1 diagram, versus only one orientation for the much more common slanted linear segment displays.
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I went back to the datasheet again and I think you’re right that the text is meant to be used as a reference point. It seems like they’re implying that they drew the part orthographically in the datasheet so the text will identify the right side of the part, and pin 1 can be located relative to that.
Also after some more extensive searching, I found this image in a Github repo which supports this.
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