TMP235: Use of temperature sensor on PCB

Aniket Kulkarni

Part Number: TMP235

I need to measure the temperature of components on the PCB by placing the sensor just on that component's PCB Polygon so as the temperature rise can be sensed as early as possible for shutdown and avoid component failures. The PCB placement is not mentioned in the application note, as which point should be placed nearer to the heat measurement spot.

over 6 years ago

0 Kelvin Le THS over 6 years ago

TI__Expert 6565 points

Hi Aniket,

Placing the TMP235 as close as possible to the heat source is adequate. Make use of metal planes to increase thermal conduction from the heat source to the sensor.
Is that polygon connected to gnd? If it is, I would place the TMP235's GND pins close to that polygon.

-Kelvin

0 Aniket Kulkarni over 6 years ago in reply to Kelvin Le THS

Prodigy 180 points

Please elaborate on the use of metal planes, as the temperature of the components to be sensed is at higher potential and thus the polygon is not connected to ground.

Also suggest some alternatives for sensing temperatures up to 170 C.

0 Kelvin Le THS over 6 years ago in reply to Aniket Kulkarni

TI__Expert 6565 points

Aniket,

Here is a good reference that talks about thermal conduction:

As you can imagine, metal is a better heat conductor than the FR4 PCB material. Thus when possible, pcb copper planes can be used to improve heat transfer from the source to the sensor. Typically, this plane is tied to ground. If this isn't possible, the next best thing to do is to place the sensor as close as possible to the source. Heat conduction is via the least thermal-resistive path.

-Kelvin

0 Aniket Kulkarni over 6 years ago in reply to Kelvin Le THS

Prodigy 180 points

Thank you so much Kelvin.

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TMP235: Use of temperature sensor on PCB