non working part....

[Cayenne]

My email to support@adafruit.com ----> I ordered a hall sensor (US5881LUA)and it did not work, upon
close inspection it is labeled U58136 - a Google search for this number
reveals nothing.??? What gives?
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PLEASE NOTICE THE WORDS "DID NOT WORK"!

My response from Adafruit----->
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Hi!

Thanks for emailing Adafruit's customer order support!

We will be able to assist your right away, our engineers and technical
support team are ready to assist you. <-----(HOW?)

For this type of question and technical support - please post up in
the adafruit customer support forums so we can better assist you as
well as help others in the process!
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I see no sub-forum for reporting bad parts. I wired it per data sheet + on left term., - on center term., output on right term. at 5 -12 volts DOES NOT WORK!!!! Could You assist Me as
well as others by sending Me a tested and working hall sensor??????

[adafruit_support_bill]

Hi,

All of our technical support is handled on the forums. This way everyone can see and learn from common problems. The vast majority of problems come down to wiring.

I wired it per data sheet + on left term., - on center term., output on right term. at 5 -12 volts DOES NOT WORK!!!!

And what about the rest of the circuit? Did you wire a pullup resistor as shown on page 7 of the data sheet?
Please describe the output a little more precisely. If it is defective we will happily replace it, but you need to give us more information.

[Zener]

I will take this opportunity to expound endlessly about part marking....

Who decides what marking goes onto a part? The manufacturer! Is there a standard? Well, not really. Are all parts marked? Nooooooo. Look at your average SMT cap, no marking of any kind. Here is the doozy: If I have a part marked a certain way, how do I determine the part number? Well, often you can't. There is no part marking lookup reference that I know of. Here is a even bigger doozy: If I know the part number, how do I know what the marking will be? SOMETIMES this info will be on the datasheet somewhere. SOMETIMES it will be in a seperate document from the manufacturer. Sometimes it is not published, you just have to buy one and take a look.

Why don't they put the whole number on the part? Generally if it is big enough they will, but many parts are too small, as in this case. And they often want to put other info on it as in this case also.

In this case, if you look up the data sheet on the part, toward the end they detail the marking, Melexis is a high quality manufacturer so they take care of details like this. What it says is the first 3 digits identify the part, in this case U58 = U5881. The next digit is the last digit of the year of manufacturer, and the last 2 digits are the week of the year. This is a date code. So your part was made in the beginning of Sept 2011.

As for why it doesn't seem to work, I will guess you are assuming it is active high out, but it is actually active low. This is shown on page 4 of the datasheet. The output is technically "open drain". What this means in this case is: If you present a south magnetic field to the face of the part it will ground the output pin. Otherwise it will let the output pin "float", like it is disconnected. It will never source any voltage. So like the support people said, you would need a pullup resistor there.

Good luck!