Precision temperature measurement in heat and cold meters

PT100/500/1000 Resistance Temperature Detectors (RTDs) are widely used in grid infrastructure and factory automation applications where high precision temperature measurement is often required. Technical requirements include either 20 mK precise Differential Temperature Measurement (DTM) for heat and cold meters from 0 to 180°C or better than 400 mK precision over the full range of -200 to 850°C for industrial sensor transmitters. This training will cover a system-level deep-dive on how using TI’s ADS1220 Delta-Sigma converter family enables precise temperature measurement in heat and cold meter applications with standard RTDs.

The 24-bit ADS1220 family of devices offers an ultra-low power, single-chip precision temperature solution for measuring up to two 2- or 4-wire RTDs in series, achieving up to 19.6 bits of effective resolution, better than 10 mK resolution and 20 mK accuracy of the DTM. Using either SPI, I2C or UART interface the ADS1220 devices can be connected to TI's MSP430FR6989 (rotation detection sensing) or MSP430FR6047 (ultrasonic flow measurement) MCUs, completing a heat or cold meter development platform.

TMP116 is a fully digital, high-precision temperature sensor, which is more accurate than the Class AA RTDs in the -55 to +125°C range with a single-point calibration. TMP116 integrates 64 bits of user data for storing calibration data and eliminates the paperwork between PT sensor and heat meter vendors.

The 2x2 mm TMP116 digital sensor with I2C interface can be built into a standard PT sensor body and connect directly to the heat or cold meter MCU such as MSP430 or CC13xx wireless MCU families. TI's TPD1E04 or TPD1E10B devices ensure compliance with EN61000-4-2 and -4-4, as required by the EN1434-4 heat meter norm.

1. Overview of temperature measurement in heat meters
2. Measuring RTD sensors with Delta-Sigma ADS1220 family
3. Differential Temperature Measurement sub-system reference design
4. Digital temperature sensor replacement of RTD sensors with TMP116

1. Overview of temperature measurement in heat meters

This section introduces the heat and cold meter training series. The series covers the basics of RTD sensors and their usage in heat and cold meters, as defined in the EN1434 set of standards.

#		Title	Duration	Overview
1.1		Overview of precise temperature measurement for heat meters TI’s ADS1220 Delta-Sigma converter enables precise Differential Temperature Measurement in heat and cold meter applications with standard PT sensors	02:25	TI’s ADS1220 Delta-Sigma converter enables precise Differential Temperature Measurement in heat and cold meter applications with standard PT sensors
1.2		RTD sensors for industrial applications Resistance Temperature Detectors (RTDs) offer linearity, long-term stability and repeatability over an extended temperature range	05:21	Resistance Temperature Detectors (RTDs) offer linearity, long-term stability and repeatability over an extended temperature range

2. Measuring RTD sensors with Delta-Sigma ADS1220 family

ADS1220 Delta-Sigma family uses the ratiometric approach for measuring RTD sensors with the built-in current excitation source. Offset and gain calibration are required before the resistance measurement is converted into a temperature reading by the application MCU.

#	Title	Duration	Overview
2.1	Ratiometric RTD measurement in heat meters SigmaDelta Precision ADC solution for temperature measurement in heat and cold meters	05:20	SigmaDelta Precision ADC solution for temperature measurement in heat and cold meters
2.2	How to measure RTDs with Delta-Sigma ADC Precision temperature measurement with Delta-Sigma analog-to-digital converters	03:55	Precision temperature measurement with Delta-Sigma analog-to-digital converters
2.3	Design process with ADS1220 for RTD sensor measurements ADS1220 temperature measurement with two 2-wire and 4-wire RTDs in a series for heat and cold meters achieves up to 19.6 bits effective resolution	11:29	ADS1220 temperature measurement with two 2-wire and 4-wire RTDs in a series for heat and cold meters achieves up to 19.6 bits effective resolution

3. Differential Temperature Measurement sub-system reference design

TIDA-01526 implements a high-precision Differential Temperature Measurement (DTM) subsystem using a 24-bit, low-power, Delta-Sigma ADC. Heat and cold meter DTM subsystems typically use two 2- or 4-wire RTDs such as PT100, PT500 or PT1000 and can achieve measurement accuracy of 20 mK over a water temperature range of 3°C to 180°C. The MSP430FR6047 application MCU converts the resistance value into a temperature reading in TIDA-01526.

#		Title	Duration	Overview
3.1		High precision temperature measurement with TIDA-01526 Differential Temperature Measurement (DTM) sub-system using ADS1220 with better than 0.02ºC accuracy for two 2-wire or 4-wire RTDs in series	08:01	Differential Temperature Measurement (DTM) sub-system using ADS1220 with better than 0.02ºC accuracy for two 2-wire or 4-wire RTDs in series

4. Digital temperature sensor replacement of RTD sensors with TMP116

The TMP116 digital precision temperature sensor for the -55 to +125ºC range achieves higher accuracy than the Class AA PT sensor with a 1-point calibration. A small PCB including TI's TPD1E10B06 or TPD1E04U04 protection devices can be sealed into a RTD metal tube and meet the EN 61000-4-2 and -4-4 levels of ESD protection. The 64-bit internal EEPROM inside TMP116 stores user defined calibration data into the digital temperature sensor, simplifying integration with application MCUs, such as MSP430FR6047, FR6989 or CC13xx/26xx wireless MCU families.

#		Title	Duration	Overview
4.1		Digital temperature sensing with TMP116 In this video we will discuss how a digital temperature sensor with built-in calibration data memory can replace PT sensors in a -55 to 125ºC temperature...	06:34	In this video we will discuss how a digital temperature sensor with built-in calibration data memory can replace PT sensors in a -55 to 125ºC temperature...

Precision temperature measurement in heat and cold meters

Table of contents

1. Overview of temperature measurement in heat meters

2. Measuring RTD sensors with Delta-Sigma ADS1220 family

3. Differential Temperature Measurement sub-system reference design

4. Digital temperature sensor replacement of RTD sensors with TMP116