Help me clear some doubts about the usage of XTR105

[466576266]

hello,anyone. recently, i am working with the temperature sensor PT100. the temp range is 0-100 degrees celsius. and i want the output is 4-20mA. and i find that the XTR105 is a good selection for my project. i know how to calculate the value of the resistor. the datasheet has given me a lot of equation. but still i have some questions:

1: the word from the XTR105 datasheet "the XTR105 is available in DIP-14 and SO-14 surface-mount packages and is specified for the -40 degrees celsuis to +85 industrial temperature range", and i donnt understand the word clearly. and my understanding is that: the measure temperature range of PT100 is just -40 to + 85, but what i want to measure is 0-100, the desired temperature range(0-100) is beyond of the datasheeet temperature range(-45 to +85). i donnt know whether i am right.



2: From the datasheet, the IC output is 4-20 mA. that's to say, in the minimum temperature ,the output is 4mA, in the maximum temperature ,the output is 20 mA. but it doesn't

give the resolution. my mean is that: if the temperature is 50.1 degrees celsuis, what the XTR105 will output ?

i donnt konw whether you understand what i mean. looking forward to your reply.

thanks.

 

[IanP]

Re: PT100 and XTR105

-40 - +85 is the range of XTR105, not PT100 ..
The PT100 has to be located some distance away from the XTR105 ..

From Table.1, for the range of 0°C-100°C the values of resistors should be as follows:
R[Z]=100Ω
R[G]=78.7Ω
R[Lin1]=33200Ω
R[Lin2]=35700Ω

With this in mind, the output current for 50.1°C should be somewhere close to 12.016mA ..

Rgds,
IanP

 

[466576266]

Re: PT100 and XTR105

-40 - +85 is the range of XTR105, not PT100 ..
The PT100 has to be located some distance away from the XTR105 ..

From Table.1, for the range of 0°C-100°C the values of resistors should be as follows:
R[Z]=100Ω
R[G]=78.7Ω
R[Lin1]=33200Ω
R[Lin2]=35700Ω

With this in mind, the output current for 50.1°C should be somewhere close to 12.016mA ..

Rgds,
IanP

thanks very much. the first problem has been solven out according to your reply.but the word "the output current for 50.1°C should be somewhere close to 12.016mA .." i just wonder how you get it(12.016ma)? from a formula, or other thing. looking forward to your reply.

 

[IanP]

Re: PT100 and XTR105

Let’s do some rough calculations without calculator (or computer) ..

From 4mA to 16mA there is 16mA span, and that’s the equivalent to 0-100 range ..

In other words, 0.1degC is responsible for 0.016mA ..
Now, 50degC is the half of the range, that is 4mA (for 0) + 8mA(for 50) => 12mA
So, 50.1degC :arrow: 12mA + 0.016mA

Rgds,
IanP

 

[466576266]

Re: PT100 and XTR105

Let’s do some rough calculations without calculator (or computer) ..

From 4mA to 16mA there is 16mA span, and that’s the equivalent to 0-100 range ..

In other words, 0.1degC is responsible for 0.016mA ..
Now, 50degC is the half of the range, that is 4mA (for 0) + 8mA(for 50) => 12mA
So, 50.1degC :arrow: 12mA + 0.016mA

Rgds,
IanP

theoretically, you are quite rught. but i just wonder whether the realistic IC operate in that way, cause i doont find anything about this part in the IC datasheet. what do you think?

 

[IanP]

Re: PT100 and XTR105

The XTR-ICs are pretty accurate devices ..
If you set them up properly you will have the expected results, have no doubts about that :!:

Rgds,
IanP

 

[466576266]

Re: PT100 and XTR105

The XTR-ICs are pretty accurate devices ..
If you set them up properly you will have the expected results, have no doubts about that :!:

Rgds,
IanP

really thank you. i konw what to do now.