MSPM0G3507: Unable to calulate internal temperature.

Sebastian Michel

Prodigy 20 points

Part Number: MSPM0G3507

Hello,

I'm unable to calculate the right temperature value. I have the following input values:

ADC digit is 1834
ADC reference voltage is 1.4V
DL_SYSCTL_getTempCalibrationConstant() returns 752
TEMP_TS_COEF_mV_C is -571.42

Now If i do the math I get:

V_SAMPLE = 1834 * 1.4V / 4096

V_SAMPLE = 0.627V

V_TRIM = 752 * 3.3V / 4096

V_TRIM = 0.606V

T = -571.42 * (0.627V - 0.606V) + 30°C

T = 18°C

I measure the internal temperature at room temperature and 18°C is too cold.

So what is wrong with my calculation?

Thanks,

Sebastian

over 1 year ago

0 Zoey Wei over 1 year ago

TI__Genius 10611 points

Hi Sebastian,

It is correct.

However, 18℃ is the internal temperature of Chip rather than room temperature.

B.R.

Zoey

0 Sebastian Michel over 1 year ago in reply to Zoey Wei

Prodigy 20 points

Hi Zoey,

as I would expect the internal chip temperature is higher than the room temperature (which is around 22°C) the 18°C doesn't seem right.

Best Regards,

Sebastian

0 Keith Barkley over 1 year ago

Guru 42085 points

Looks like they read low.

I just got 16.6 degrees C on mine using the example from the latest SDK.

0 Zoey Wei over 1 year ago in reply to Sebastian Michel

TI__Genius 10611 points

Hi Sebastian,

I am not sure 18℃ is the definitely correct in your case. But this data seems to be reasonable for the temperature of the chip itself.

Maybe you can use a thermometer to actually measure the temperature inside the chip and compare it.

0 Keith Barkley over 1 year ago in reply to Zoey Wei

Guru 42085 points

"Maybe you can use a thermometer to actually measure the temperature inside the chip and compare it."

How would this work? As a semiconductor engineer I am dying to know.

While in absolute terms 18C is a reasonable number, if the ambient is 22, unless the chip is violating the 2nd law, it is impossible for it to be *cooler* than its environment.

I note that there are no accuracy specs given, so I suspect that there is a 3-4 degree error possible.

0 Zoey Wei over 1 year ago in reply to Keith Barkley

TI__Genius 10611 points

Sorry, I mean use thermal imager not thermometer.

Actually, we have recently been retrimming the temperature sensor internally, thanks for the news that gave us.

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MSPM0G3507: Unable to calulate internal temperature.