Design Details for TI design TIDA-00834 High Accuracy Analog Front End Using 16-Bit SAR ADC with ±10V Measurement Range Reference Design
Fifth part of the session will focus on providing detailed information on TIDA-00834 TI design. The initial slides cover Design Overview, Features, Key Components, test Setup, market differentiators, Block Diagram with links to relevant TI Designs, EVMs and TI product used in this design. Circuit representation and detailed description for ADC interface, Voltage and Current measurement and Power supply are provided. Graphs for Voltage and Current measurement accuracy are shown; along with collaterals and TI design links that can be referred by customers during design.
This section covers the basics of mechanical water meters and the principle of operation for impeller based water meters. There are multiple standards for water meters around the world; the EN ISO 4064 is relevant to all European countries and has been adopted under a different name in some other regions as well.
Water and heat meters share multiple system building blocks, such as the metrology sub-system and the application sub-systems, the Wireless communications part, the InfraRed optical port or the power solution. In this section, we will cover a new ultra-low cost single-chip LC-sensing solution utilizing the CC1350 Wireless MCU and its Sensor Controller Engine. Two external LC-tanks with a TI FemtoFET device each implement two rotation detection sensors, which measure the rotation of a half-metal/half-nonmetal disc, often used in mechanical water meters.
Some EU standards like EN1434-3 for heat meters require optical interface as per EN62056-21, where two separate IR LEDs are used (one for receive and one for transmit direction). TIDA-01212 shows an alternative approach, which uses a single IR LED to implement a bi-directional IrDA PHY link with 9.6 kbps in half-duplex mode. The design approach can the system reduce cost of any smart (sub-)metering device by replacing the legacy optical IrDA PHY modules with two separate LEDs.
This module covers the “Innovative 7-Segment LCD Control Using GPIO Pins and SW” section of the “Single-chip Smart Water meter with Dual-band RF link and InfraRed port” training series.
For anti-tampering, it is common to try to detect the presence of a strong magnet. In this section, we will cover the use of hall sensors for low-power detection of strong magnetic fields in three dimensions. Details on our magnetic tamper detection reference design, TIDA-00839, will be provided as well as some of the design considerations that were kept in mind when creating this reference design.
In this section, we will cover how to harden a meter against these magnetic tamper attacks by using shunts for current sensors. For poly-phase implementations, I will go over how to use isolated delta sigma modulators to add the necessary isolation to use shunt current sensors and create magnetically immune poly-phase energy measurement systems. The TIDA-00601 and TIDA-01094 reference designs, which show how to implement a poly-phase isolated shunt measurement system, will be discussed as well as the associated AMC1304 high-side power supplies used in these designs.
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.
This section covers what is meter tampering and why is this a problem for utility providers. It also covers the advantages of shunt current sensors. In addition, it introduces the isolated modulator and isolated metrology AFE architectures for adding isolation to shunts.
For both isolated modulator and isolated metrology AFE architectures, high-side power supplies are needed for each phase. In this section, the different high-side power supply options that are available are discussed, which include cap-drop power supplies, isolated DC/DC power supplies with external transformers, as well as isolated DC/DC power supplies with transformers integrated.
In this section, the isolated metrology AFE architecture will be discussed. The software and hardware design considerations for this architecture will be discussed. In addition, the TIDA-01550 isolated metrology AFE reference design will also be discussed.
In this section, the isolated modulator architecture will be discussed. The software and hardware design considerations for this architecture will be discussed. In addition, various isolated modulator designs will also be discussed and compared.
Both isolated modulator and isolated metrology AFE architectures have their advantages with respect to each other. Depending on system requirements, one architecture may be more feasible than the other. This section compares the two isolated shunt sensing architectures and discusses which architecture is best for different system requirements.
In this section, a summary of the entire “Polyphase Current Measurement with Isolated Shunt Sensors” training module would be covered. Links will be provided for the reference designs that were discussed during this training series.