• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 30 subscribers
  • Views 248 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TMP431: Custom diode temperature reading problem with TMP431

Danilo A.
Mastermind 28680 points
Part Number: TMP431
Other Parts Discussed in Thread: DXP

Hi Team,

Can you please help us with our customer's inquiry below?

I'm working on a diode, of which i am attaching the characteristic.

Diode_char.pdf
I want to read the temperature using a TMP431, but i can't find the right η and Beta parameters.
With register 0x25 (Beta Register) set to 0x07 (manually disabled beta correction),
and register 0x18 (N-factor correction) set to 0x7F i read 0x7C (60°C), instead of the espected 25°C.
Changing the register 0x18 with lowest values the measure goes out of scale.

Can you suggest a registers configuration for this type of diode?

Regards,

Danilo

  • 0
    TI__Mastermind 43805 points

    Could you please check what beta range TMP431 chooses when left in auto beta range mode? With register 0x25 set to 0b00001xxx, wait for remote conversion to complete, then read register 0x25. With the default conversion rate, this shouldn't take more than 2*tconv or around 300ms.

    Could you please get an oscilloscope capture of an active measurement on the DXP pin? There should be about 130ms of activity on the pin followed by some idle time before another measurement begins. During the 130ms, there will be 4 distinct voltage levels that are toggled dozens if not more than a hundred times. I need to see this toggling to understand your diode's behavior.

    Your attached document states 20uA max. Can you elaborate? All remote temperature sensors source over 100uA, making this technology potentially incompatible with your diode. 

    thanks,

    ren