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| resources:eval:user-guides:eval-ad7441x:tools:thermocouple [28 Jun 2021 11:39] – Feedback edits Bríde Ní Riagáin | resources:eval:user-guides:eval-ad7441x:tools:thermocouple [14 Sep 2021 16:11] (current) – updated link back to TOC Bríde Ní Riagáin | ||
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| =====Thermocouple & Cold Junction Compensation Measurements with AD74413R===== | =====Thermocouple & Cold Junction Compensation Measurements with AD74413R===== | ||
| - | ~~NOTOC~~ | + | |
| ====Introduction==== | ====Introduction==== | ||
| The AD74413R is a quad channel software configurable I/O IC that provides multiple analog and digital functions to a single pair of screw terminals. The AD74413R is configured over a single SPI interface. The part offers Voltage/ | The AD74413R is a quad channel software configurable I/O IC that provides multiple analog and digital functions to a single pair of screw terminals. The AD74413R is configured over a single SPI interface. The part offers Voltage/ | ||
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| \\ Refer to figure 1 for a high level block diagram of the required connections for thermocouple measurements. | \\ Refer to figure 1 for a high level block diagram of the required connections for thermocouple measurements. | ||
| + | \\ | ||
| + | \\ The thermocouple generates a voltage that is proportional to the temperature difference between the measurement point and where the thermocouple is connected at the screw terminals, the cold junction. | ||
| + | To be able to determine the temperature at the measurement point, the cold junction temperature must be measured along with the voltage generated by the thermocouple. | ||
| \\ The thermocouple should be connected between the I/OP and I/ON screw terminals. The AD74413R can be configured in Voltage Input mode, with the ADC range set to the ±104.16mV to measure the small voltage generated by the Thermocouple measurements. | \\ The thermocouple should be connected between the I/OP and I/ON screw terminals. The AD74413R can be configured in Voltage Input mode, with the ADC range set to the ±104.16mV to measure the small voltage generated by the Thermocouple measurements. | ||
| \\ The AD74413R can support cold junction compensation measurements by measuring the response from an external thermistor resistor divider using the onboard diagnostics. The LVIN pin can be used to measure the thermistor voltage within an ADC range of 2.5V. The resistor divider can be placed close to the terminal pins where the thermocouple is connected. | \\ The AD74413R can support cold junction compensation measurements by measuring the response from an external thermistor resistor divider using the onboard diagnostics. The LVIN pin can be used to measure the thermistor voltage within an ADC range of 2.5V. The resistor divider can be placed close to the terminal pins where the thermocouple is connected. | ||
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| ====Implementation==== | ====Implementation==== | ||
| - | Two measurement steps are taken to determine the temperature of the Thermocouple hot junction. | + | Two measurement steps are taken to determine the temperature of the measurement point. |
| \\ First, the cold junction temperature is measured to establish a reference point for the thermocouple. | \\ First, the cold junction temperature is measured to establish a reference point for the thermocouple. | ||
| Figure 2 shows a snapshot from the AD74413R evaluation board. This circuit shows the implementation required to use the AD74413R to determine T< | Figure 2 shows a snapshot from the AD74413R evaluation board. This circuit shows the implementation required to use the AD74413R to determine T< | ||
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resources/eval/user-guides/eval-ad7441x/tools/thermocouple.txt · Last modified: 14 Sep 2021 16:11 by Bríde Ní Riagáin