Device for flow sensing runs on µAs

When capturing flow measurements from external ultrasonic transducers at a rate of 8 measurements per second, the TDC-GP30-F01 flow-sensor converter draws a continuous current of only 8.5 µA — so little it could operate for up to 20 years on a single AA lithium battery. Intended for cold-water meters, the sensor supports design of systems that offer very accurate measurements of water flow and volume, making it suitable for use in water metering applications that are regulated by law. And because of its built-in functionality, designers can easily use the converter to quickly create an ultrasonic water meter, without the need to develop their own firmware.

Added to the company’s product lines as a result of a recent acquisition, the TDC-GP30-F01 measures the difference in the time it takes ultrasound waves to travel upstream and down, enabling repeatable, temperature-stable, and accurate timing measurements. In a good DN20 meter design, the converter allows detection of water leakage rates as low as 0.5 liters per hour — many times lower than the minimum water flow measured by today’s mechanical meters.

The converter integrates an ultrasonic-flow-measurement front-end, a low-power, a 32-bit measurement-data processor, and firmware for converting analog transducer outputs to measurements — of cold-water flow rate, volume, and temperature. In addition to the ports for connecting ultrasonic transducers, the chip provides an SPI/UART interface for direct connection to a simple external microcontroller for operating a water meter’s peripheral functions, such as a display and connectivity. The converter also has a pulse-output port to emulate a conventional mechanical water meter’s signals.

Users have the option of adding their own firmware code to the device, to implement, say, a heat-meter application. The device’s manufacturer also provides a full suite of hardware and software tools for evaluating, developing, and characterizing designs using it. The company also offers firmware functions, such as error handling, as well as power-saving modes when the flow rate is zero. The TDC-GP30-F01 is priced at $9.50 ea. / 1,000 and is available in sample and production quantities now, as is a demonstration kit.