Post Go back to editing

# AD4110-1 output raw value convert into degree Celsius for RTD 4W sensor

Hi,

I wants to convert output raw value of AD4110-1 into degree Celsius for RTD 4W sensor.

Can some one pls help me for how to convert raw value into temperature?

Thanks,

Jaydip

## Top Replies

Parents
• Hi,

The conversion of raw data of AD4110-1 into degree celsius will depend on the RTD sensor,Sense Resistor, PGA and the configuration being used. The sensor would have the transfer function which needs to be multiplied for the conversion.

Thanks

Vikas J

• Hi,

Just to add. You have to get the equivalent resistance measurement of the RTD in order for you to calculate the equivalent temperature using the RTD transfer function. The Callender-Van Dusen equation, gives a more accurate result. So I suggest you can use it.

Please refer to this Circuit note for the equation. CN-0383 (Rev. C) (analog.com)

The RTD transfer function can be used directly from this. However, the RTD resistance measurement from code is different from AD4110 as it uses a different scheme. So Ideally you just need to convert the measurement code in voltage and divide it with excitation current. But as Vikas stated it depends on the selected excitation current, PGA settings, etc.

Thanks,

Jellenie

• Hi Jellenie ,

Thanks for the answer!

The Callender-Van Dusen equation is helpful for RTD conversion.

is this equation use for Thermocouple conversion also or not?

Thanks,

Jaydip

• Hi,

The TC have different transfer function. We also have reference circuit for this. Ideally you need an external CJC for TC. Here's the circuit note to guide you through. For TC we usually used some kind of a look up table from the NIST website depending on the type of and temperature range.

CN-0384 (Rev. A) (analog.com)

Thanks,

Jellenie

• Hi,

In Callender-Van Dusen equation, How to find Rref (in equation 6, page 3 CN-0383).

or

Do you have any Application example code for Convert  ADC(AD4110-1) RAW code into degree Celsius for RTD and Thermocouple ?

Thanks,

Jaydip

• Hi,

In Callender-Van Dusen equation, How to find Rref (in equation 6, page 3 CN-0383).

or

Do you have any Application example code for Convert  ADC(AD4110-1) RAW code into degree Celsius for RTD and Thermocouple ?

Thanks,

Jaydip

Children
• Hi,

Rref is a given value, it is the value of the reference resistor used to generate the Vref. For CN-0383 the reference voltage is driven by a reference resistor of 5.11kohm. AD4110 uses a different scheme. So ideally you just need to get the equivalent voltage from the data output code and then get the RTD resistance from the measured voltage and excitation current used. I think the datasheet mentioned how to convert data output to equivalent voltage.

We only have reference code here to configure the ADC that you may also find helpful. But I'm not sure with if they have specific code for temperature measurements.

Jellenie