DLP4710EVM-LC: About the temperature acquisition command

Keisuke Goto

Part Number: DLP4710EVM-LC
Other Parts Discussed in Thread: DLPC3479,

Hi,

I have a few question about the temperature acquisition command.

(1) Is the temperature calculated using the B constant of the thermistor?

(2) What is the temperature range of the B constant you are using for temperature calculation?
Also, how does the DLPC3479 behave when the thermistor exceeds that temperature range?

(3) Is it possible to change the FW of the DLPC3479 if I want to use a thermistor with a different B constant than the one installed in the EVM?

Regards,

Goto

over 4 years ago

0 Mayank Khandelwal over 4 years ago

TI__Genius 9971 points

Hello Goto,

I will reach out to the team to gather more information related to your queries.

It may take some time because of the current holiday period.

Regards,

Mayank

0 Keisuke Goto over 4 years ago in reply to Mayank Khandelwal

Intellectual 600 points

Hi Mayank-san,

Thank you for your response.

I am waiting for your answer.

Regards,

Goto

0 Mayank Khandelwal over 4 years ago in reply to Keisuke Goto

TI__Genius 9971 points

Goto-san,

Thanks for your patience. We will update you once we have all the relevant information.

Regards,

Mayank

0 Philippe Dollo over 4 years ago in reply to Mayank Khandelwal

TI__Mastermind 28005 points

Goto-san,

Some feedback from me on the above:

You are correct that the B-constant of the thermistor is used to calculate temperature. If you change either of the B-Constant or the Resistance you would need a new lookup table (LUT) installed to the firmware to support the new component.

What component are you looking to use in your system?

Regards,

Philippe Dollo

0 Keisuke Goto over 4 years ago in reply to Philippe Dollo

Intellectual 600 points

Philippe-san,

Thank you for your response.

I understand that it is possible to change the LUT.

I'm still working out the details, but if I need to change it, I'll consult you again.

Regards,

Goto

0 Keisuke Goto over 4 years ago in reply to Philippe Dollo

Intellectual 600 points

Hi Philippe,

Sorry, I have an additional question.
Could you please tell me the value of the LUT?

REgards,

Goto

0 Philippe Dollo over 4 years ago in reply to Keisuke Goto

TI__Mastermind 28005 points

Goto-san,

The LUT captures the relationship between the voltage of the thermistor to the input comparator and the temperature of the thermistor. This array is affected by the B-Constant and resistance of the thermistor, as well as divider resistance. The LUT must be changed when any of the preceding values are changed.

Regards,

Philippe Dollo

0 Keisuke Goto over 4 years ago in reply to Philippe Dollo

Intellectual 600 points

Hi Philippe-san,

Thank you for explaining about the LUT.

I assume you are defining LUT values for each certain temperature range(for example 10° increments), but what temperature range do you configure your LUTs for?

Also, the thermistor in the DLP4710EVM-LC has an operating temperature range of -40 to 120°. Does the LUT cover the -40 to 120° range?

Regards,

Goto

0 Philippe Dollo over 4 years ago in reply to Keisuke Goto

TI__Mastermind 28005 points

Goto-san,

You are correct. The LUT does cover the full -40 to 120 range, and does so in 5 degree increments.

Regards,

Philippe Dollo

0 Keisuke Goto over 4 years ago in reply to Philippe Dollo

Intellectual 600 points

Hi Philippe-san,

Thank you very much for your kind support.

Regards,

Goto

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DLP4710EVM-LC: About the temperature acquisition command