New Ultrasonic Time-of-Flight IC with Transducer and Processing

TDK has recently unveiled a groundbreaking MEMS piezoelectric ultrasonic time-of-flight distance sensor, the ICU-10201, housed within a compact 3.5 x 3.5mm package that includes its signal chain.

"The ICU-10201 offers the sensitivity necessary for obstacle avoidance or proximity sensing, making it ideal for applications in robotics, drones, and robot vacuum cleaners," stated a representative from the company. "This sensor delivers millimeter-accurate range measurements to targets up to 1.7m away, regardless of lighting conditions or the target's color and optical properties, such as glass or mirrors."

At a distance of 1.7m, the sensor can accurately detect a wall, with the range decreasing to 1.1m for a 58mm diameter post. The sensor's precision is influenced by the speed of sound's 0.2% drift per degree Celsius. While the minimum range is 100mm, objects as close as 30mm can still be detected and sometimes ranged.

The chip itself is a mere 1.26mm tall and features a central sound port on its top, offering a hemispherical field-of-view that can be adjusted using an external horn. By varying the horn's diameter, users can achieve narrower beams. TDK provides design data for various horn options. The sensor operates sonically at a nominal frequency of 175kHz, with resonance ranging from 173 to 181kHz due to manufacturing tolerances.

Equipped with a 40MHz microcontroller, the sensor can process raw readings into range data for multiple objects simultaneously, as well as detect events like presence. This information is transmitted to a host device via SPI communication running at 13MHz and either 1.8V or 3.3V.

TDK also offers SonicLib, a driver software designed for the host microcontroller. Written in C, SonicLib is compiler and microcontroller-independent. It facilitates the control of one or more ICU-10201 sensors connected to host SPI ports, enabling programming, configuration, triggering, and data retrieval. According to TDK, the driver only requires customers to implement an I/O layer for communication with the host processor's SPI and GPIO hardware.

For scenarios where one device must serve as a transmitter for others nearby, a specialized version called ICU-10201-PC ('pitch-catch') is available. This variant features a narrower part-to-part resonant frequency variation of 176 to 178kHz. The sensor requires three power rails: analog (1.71 to 1.89V), digital (same range), and IO (1.71 to 3.63V).

With power consumption dependent on range and update rate, a single CU-10201 can draw varying currents, such as 14µA for a 0.5m range at 1 sample per second, 17µA for a 1m range at the same rate, 212µA for a 0.5m range at 50 samples per second, or 320µA for a 1m range at 50 samples per second. The sensor's operational temperature range spans from -40 to 85°C.

Applications for this innovative sensor include obstacle avoidance in robotics and drones, cliff detection for vacuum cleaners, identification of soft surfaces, and liquid level measurement, such as in coffee machines. The ICU-10201 opens up a world of possibilities for precise and reliable distance sensing in a variety of scenarios.