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PSoC Creator & Designer Software

ETRO_SSN583
Esteemed Contributor

In Creator, DieTemp module datasheet, there is no discussion or data

   

on its output V vs T characteristics. Would be useful in case one does not

   

want to use injection channel, just plain SAR or DelSig.

   

 

   

Nor does the datasheet cover this. Or linearity. All it covers is accuracy,

   

no clue what its voltage is doing.

   

 

   

Regards, Dana.

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3 Replies
RobynW_26
Employee

I've let the dev team know.

   

 

   

-Robyn

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Anonymous
Not applicable

 In PSoC 4 the die temp sensor is only connected to the positive input of the SAR.  If you were to send it to some other destination, then it would consume the routing for the positive input of the SAR making the SAR otherwise unusable. The die temp sensor was designed with the drive strength to connect to the SAR and not to other destinations. This means that it can only be used in conjunction with the SAR. You can hook the die temp up to the injection channel or to one of the other SAR ADC channels.  

   

As the datasheet describes the SAR should be configured to measure a single ended voltage between 0 and 1.024V as an unsigned 12 bit value.  The API provided with the Die Temp component then takes this unsigned 12 bit value that represents a voltage between 0 and 1.024V and converts it to temperature.  The Voltage to Temperature relationship is non-linear.  To approximate this curve the conversion function uses a piece wise (2 pieces) linear equation.  The coeffecients for this equation are trimmed specifically for each individual device.  The algorithm reads the trim data from locations that were written as part of the manufacturing process based on the characteristics of the device.  We don't describe the details of this calculation, but the source code of the computation is provided as part of the component.  If you would like to understand the exact details of the conversion, then build a design that includes the Die Temp component and review the CountsTo_Celsius() function that is generated.

   

 

   

 - Brad

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ETRO_SSN583
Esteemed Contributor

Brad, then you could not use a comparator on the DieTemp

   

module and detect a T alarm over/under condition ? Eg. you

   

are stuck using SAR ?

   

 

   

Regards, Dana.

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