# Magnetic Sensor Sensitivity units mV/V/gauss, etc.

1. Aug 2, 2012

### VinnyCee

So I've been looking at magnetic sensor datasheets and I see the sensitivity is usually listed in units of mV/V/gauss. What does this mean?

Let's say I need to sense changes in a magnetic field that usually ranges from about 10 gauss ( 1 mT ) to about 130 gauss ( 13 mT ). And I need to be able to sense 0.12 gauss ( 12 Î¼T ) differnces in the field ( basically the range divided into 1000 equal parts ).

How would I calculate the sensitivity range that would be sufficient for such an application?

2. Aug 2, 2012

### voko

Such a sensor has input voltage and output voltage. Hence you get how the output voltage changes per input voltage per the field measured. Assuming your input voltage is very stable, or you can account for its fluctuations in some other way, this then becomes output voltage per field. Any major manufacturer of such device should have some literature that will explain this in more details and offer some design guidance.

3. Aug 2, 2012

### VinnyCee

So lets say for the HMC1021/1022 by Honeywell, which has a sensitivity of 1.0 mV/V/gauss, this would mean that for every 1 gauss change in detected magnetic field, there would be a 1 mV change in output?

I notice there is lots of other information there, seems a bit overwhelming at first! I am most concerned with sensitivity, linearity and repeatability. All of these are described in the datasheet, but I'm not sure how to correlate what I need (described above) into what it would say on a datasheet for a suitable product. Any advice?

4. Aug 2, 2012

### voko

You need to factor in the input voltage. On that same datasheet, it is specified as a range from +2V to +12V, with the typical being +5V. With that voltage stable, the sensitivity will be 1.0 mV/V/Gauss x 5V = 5.0 mv/Gauss.

I am not an EE guy, so even if I give you advice in this area, don't listen to me. I just (I hope) I know the underlying physics, but when it comes to systems design I would be completely clueless. If what you do is for some laboratory project, you probably could get a digital magnetometer from them, such as this one http://www51.honeywell.com/aero/com...alog-documents/Missiles-Munitions/HMR2300.pdf and spare yourself a lot of trouble.

5. Aug 2, 2012

### VinnyCee

I sent an email to a few manufacturers to inquire about what products they may have which would be applicable here. Hopefully they'll get back to me soon with some good news!

It's not for a lab project, I'm trying to use it to make a device.

Using the info in the OP, can anyone tell me what I should be looking for in the fields "sensitivity", "linearity", and "repeatability" fields in a prospective device's datasheet?