MSPM0G3507: About Temperature Sensor calculation

kei

Part Number: MSPM0G3507

Hello.

I have a question regarding the temperature conversion formula for MSPM0G3507.

1. Checking how to use Temperature coefficient in calculations
TRM states that temperature is calculated using the following formula.
TSAMPLE = (1 / TSc) ∗ (VSAMPLE - VTRIM) + TSTRIM
TSc is Temperature coefficient.

Sample program for SDK 1.20.01.06
In "adc12_internal_temp_sensor_mathacl", the value of 1/TSc is -571.42f.
Calculating TSc from -571.42f resulted in -0.001750.

Chapter 7.12 of datasheet_mspm0g3507_revB states that the TSc TYP is -1.8mV/℃, but I think -1.75mV/℃ is correct.

2. About the calculation formula of VSAMPLE
In TRM, the formula for calculating VSAMPLE is written as:
VSAMPLE = (VREF / 2RES) ∗ (ADCCODE - 0.5)
2RES is calculated as 4096, but if the maximum ADCCODE is 4095, I think 2RES needs to be 4095 as well.

over 1 year ago

0 Cash Hao11 over 1 year ago

TI__Mastermind 46765 points

Hi,

1. I agree with you, we are using -1.75mV/℃ to get the 1/TSc value.

2. the maximum is 4095, however, the range is from 0 to 4095. So it has a total of 4096 data points. I think it should use 4096 in this formula.

Best regards,

Cash Hao

0 kei over 1 year ago in reply to Cash Hao11

Intellectual 685 points

Cash Hao11,

thank you.
I agree with questions 1 and 2.

Sorry for adding this, but what do you mean by 0.5?

0 Cash Hao11 over 1 year ago in reply to kei

TI__Mastermind 46765 points

Hi,

What 0.5 you mentioned here？

Best regards,

Cash Hao

0 kei over 1 year ago in reply to Cash Hao11

Intellectual 685 points

sorry.
I am referring to 0.5 in the equation below.
VSAMPLE = (VREF / 2RES) ∗ (ADCCODE - 0.5)

0 Cash Hao11 over 1 year ago in reply to kei

TI__Mastermind 46765 points

Hi,

Well, I checked in the TRM. Equation 2. It already has the -0.5 in the formula. I do not know the reason why it is there. I also saw when calculating the Vtrim value, it also has the -0.5 in the formula. So, it make sense that the Vsample keeps the same as Vtrim formula.