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Negative Temperature Coefficient

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soumen21

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Hi,

NTC part no. ERT-D3FFK300S is used in one of a very old design. The part is obsolete now. Can we replace ERT-D3FFK300S with B57164K0330K000 ?

Datasheets are attached for reference.

Regards
 

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They are not exactly apples to apples. They are a little different at rest (30 ohm to 33ohm) but the bigger issues is the B values are different. The B values define the temperature profile curve and how they react over the range (as defined by the Steinhart-hart equation). You would have to see how much different this results in from the 300B value difference. So if you have a tolerance band then it may be feasible.
 

cl10greg said:
They are not exactly apples to apples. They are a little different at rest (30 ohm to 33ohm) but the bigger issues is the B values are different. The B values define the temperature profile curve and how they react over the range (as defined by the Steinhart-hart equation). You would have to see how much different this results in from the 300B value difference. So if you have a tolerance band then it may be feasible.
Click to expand...


Hi,

Yes there are differences. The existing part has 30 Ohms with a tolerance of 10% and Beta value of 3000 with 10% tolerance. And the new part has a Beta value of 2900 with 3% tolerance and resistance of 33 Ohms with 10% tolerance.
 

Do you care how much error there is?
Have you tried to calculate Sensitivity Analysis? ( partial derivative of equation)

Then determine max error due to difference in R25 and B over your specified operating temperature range?
Then see what other changes are needed with fixed resistors are necessary?
 

The B value defenitions of both the parts seems to be different. One defines it as R25/R50 and the other as R25/R100. So i think the difference is more than 300B.
 

techgreed said:
The B value defenitions of both the parts seems to be different. One defines it as R25/R50 and the other as R25/R100. So i think the difference is more than 300B.
Click to expand...

Yea I skimmed and didn't put the right number but the point being that it is different so based on the tolerance for measurement, you would not have an equivalent system.
:p
 

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