Power-Supply Rejection MAX31855 is -0,30 °C/VHi, I have a question on MAX31855. I am wondering how the VCC is controlling the resolution ? My actual temperature range is -150 C to +150 C and I would like to have resolution of about 0.25 C. What is the effect of long wire thermocouples with 3 meter on the accuracy of readings ?
Hi,
I guess there should always be a cold end reference temperature which has to be at the same temperature all the time which is a challenge and that effect the accuracy. Then I guess RTD is better option to get 0.25 C precision for temperature range -150 C to +150 C.
Is there any 8 channel RTD current source ? or a IC which can read 8 RTDs ?
Does it also contain the reference temperature sensor inside to read the T- ?
The datasheet is rather clear with this. You need to read the datasheet and follow the schematics and design recommendations.I am wondering do I need to provide a maintained temperature reference surface for T- outside the chip MAX31856 ? or I just need to connect thermocouple's terminal T+ and T- to the chip and trust the reading that comes out even if the cold junction reference temperature changes ?
Then you did not read a documentation about thermocouple temperature measurement.I don't understand the term cold junction.
Thermocouples produce a voltage when two dissimilar metals are connected with the two junctions at two different temps.Hi,
I am looking for electronics circuit for reading K type thermocouples. I have looked at some references but not able to understand where we need to apply voltage to power them up. It just says that one terminal has to be on the common reference temperature point which at some places is referred as cold junction and then we just measure the voltage across the thermocouple but the question is where the biasing voltage come from ?
According to the datasheet, the reference measurement is automatically added to the thermocouple output. You don't need to do anything about it.I am wondering how to include 12 bit internal reference measurement towards the calculation of actual temperature ?
The device senses and corrects for the changes in the reference junction temperature with cold-junction compensation. It does this by first measuring its internal die temperature, which should be held at the same temperature as the reference junction. It then measures the voltage from the thermocouple’s output at the reference junction and converts this to the noncompensated thermocouple temperature value. This value is then added to the device’s die temperature to calculate the thermocouple’s “hot junction” temperature. Note that the “hot junction” temperature can be lower than the cold junction (or reference junction) temperature.
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?