TMP007 sensor

Hi Dan,

200PSI is quite a bit of pressure, if any objects somehow travel through the air input device and hit the TMP007 could damage the array of thermopiles on the surface of the package. I would recommend building a casing around the TMP007 and add an IR filter material that acts as a lens to protect the IC itself. You would still be able to detect the IR through the IR filter material. We have characterized some IR filters and have found a thin piece of polyethlyene to be an ideal filter.

-Michael Wong

Hi Dan,

Another suggestion is to use what we call the backside via approach. The backside of the TMP007 will be used to detect IR through a via in the PCB. This does two things, one is that it provides a narrower field of view to get more accurate temperature readings and two is that it will protect the IC from any high pressure/velocity  objects that may damage the package. See the picture below:

Let me know if you have any other questions.

-Michael Wong

Thanks Michael, I would like to try the IR filter first as the sensor board is already made. You said you have found some IR filters. Could you please send me this info?

Thanks Much.

Dan Ross - AST INC.

Hello Michael, another couple of questions. I'm assuming the IR filter you found is a IR transmission filter - correct? Also, I included a .5" spacer in the 'sensor tube' for exactly this purpose - not being 100% sure. Does this sound right that the IR filter itself will be mounted on the spacer .5" away from the surface of the sensor?

Hi Dan,

Yes the IR filter is an IR transmission filter.

I am unclear of your explanation, can you provide a simple diagram of the spacer and the filter mounted on the board?

-Michael Wong

Hello Michael.

The spacer is just that. A circular hollow piece of black ABS that has a height (or width if you prefer) of .5" and seats against the outer edges of the PCB that has the sensor. The I.R. filter would be attached to the spacer giving .5" distance from the sensor's surface to the incoming air.  All of this is mounted inside a aluminum tube that has the inside black anodized.

Also, please don't forget to send me info on the I.R. filter material you found.

Thanks much.

Dan Ross

Hi Dan,

That spacer sounds about right.

Here is a chart of materials that can used as a window material (not IR filter material as mentioned earlier). We are mainly interested in the 4-16um range.

The material we have characterized as a window material is polyethlyene and have found good success with it.

-Michael Wong

Polyethylene  also passes visible light. I'm under the impression I should be looking for a window material that blocks the visible light spectrum and paases the THERMAL IR spectrum (3 - 16 um) which the chart shows either Germanium or Zinc Selenide being the best choices.

Have you (T.I) tried these other materials? Is Polyethylene 'good enough'?  Which way am I going?

Thanks

Dan Ross

Hi Dan,

The TMP006 will only detect IR spectrum wavelengths (4-16um) and does not care about the visible light spectrum. In my posts above I made the mistake of mentioning polyethylene, it should be polypropylene, I keep getting those two mixed up. The specific material we have tried is this one: www.edmundoptics.com/.../.

Also check out this other E2E topic that covers a lot about IR windows: e2e.ti.com/.../1666830

-Michael Wong