Based on time-to-digital conversion technology for precision time-of-flight measurement, the ultrasonic flow converters operate the analog front end to drive and read transducers, detect the zero crossing in the receive signal and measure the travel time of the ultrasonic bursts. The whole front-end is optimized for ultra-low power operation. Besides pure front-end devices, ams also offers flow converters which integrate a low-power 32-bit CPU to calculate the flow. Some are supplied with the flow firmware on-chip. The devices communicate via SPI, but for stand-alone applications the output may be provided via a pulse interface.