Tamura L37S100S05M 5V current sensors defective or datasheet confusion?

We picked up two off L37S100S05 (Digi-Key PN 132-L37S100S05M-ND) for a quick prototyping on a solar power instrumentation project, and we’re not getting test bench results that are anywhere close to the datasheet (as best we can interpret it). Datasheet is here to save time.

Vcc is 4.99V from a test bench PSU, and according to the datasheet Vref the “Reference voltage (output)” should be 2.475 / 2.495 / 2.515V (min/typ/max) at 0A current. We are measuring 3.01V on one, and 3.02V on the other.

Under the same conditions at 0A the datasheet says the output voltage should be “Vof + 0 625V ± 0 015V” [sic]. When no external Vref is applied it looks like Vof should be the same as Vref i.e. 3.01V from above, meaning we might expect an output 3.01+0.625 = 3.635V. We are measuring 0.53V

The numbers do not correspond to the datasheet at all.

We haven’t worked with these types of sensors very much, but have diligently tried to use the datasheet. Any help or advice on how to actually use these before we give up and return them or throw them in the defects bin would be really appreciated!

Edit: typo

Hello @cwynd,
When testing the part do you have the 10Kohm RL resistor connected between Vout and GND?

Hi @ScottRaeker, thanks for the question - yes we do!

Seems interesting that you are measuring 3.01 on Vref and 0.53 on Vout. When you subtract 0.53 from 3.01 you get 2.48 (which is the nominal Vref range per datasheet. Are you sure you are measuring between pins 1 and 3 for Vref and 2 and 3 for Vout?



Thanks, that’s a very good observation!
We’re using a prototyping breakout board, and I just got the tech to go back and recheck that part of the wiring another time based on your observation, and he found an error. Once he corrected that we are now measuring nominal datasheet values, and back on track.
I should have been more suspicious when the results for both pieces were identically wrong.

Thanks for sticking with us through our stupidity @ScottRaeker and apologies for wasting everyone’s time.


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