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[FAQ] Ultrasonic Sensors

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Ultrasonic sensing uses the propagating sound waves at a frequency above the range of human hearing (>20kHz) that can travel through a wide variety of mediums (air, fluid, or solid) to detect objects, measure distance, or track disturbances. Ultrasonic sensors can be used to detect a wide variety of materials regardless of shape, transparency, or color.

For an overview on ultrasonic sensing fundamentals, TI recommends you begin by reading the Ultrasonic Sensing Basics application note.

TI offers a variety of ultrasonic sensing ICs. The objective of this FAQ is to help recommend a specific TI ultrasonic sensing device based on the application use-case and system requirements.

Ultrasonic Sensing Application

Measure Distance and Proximity

Measure Level or Height of Liquid or Solid

Measure Flow Rate and Direction of Liquid, Gas, or Heat

Measure Concentration and Material Identification

Object Tracking and Mapping

Material Thickness and Flaw Detection

Monitor Changes to Environment

Description

Use a single sensor to both generate and capture a round-trip time-of-flight echo to measure the distance between the sensor and the targeted object.

Use a single sensor to both generate and capture a round-trip time-of-flight echo to measure the distance between the sensor and the targeted object.

Use two sensors to capture the difference of transit time propagating in and against the flow direction as an independent upstream and downstream measurement.

Use a single sensor to both generate and capture a round-trip time-of-flight echo to measure the changes in the speed of sound based on a fixed-known distance.

Use at least two transducers with a fixed-known distance between on another. One transducer must always be used to generate and capture a round-trip time-of-flight echo, while the other transducers must only capture the round-trip time-of-flight echo. By comparing the resulting time of flight differences through triangulation.

Use a single sensor to both generate and capture a round-trip time-of-flight to measure the thickness of a solid object, and determine if there are any voids within the solid. The transducer face must be made to couple to the solid material type for direct transducer to solid contact.

Use two transducers, one to continuously generate the ultrasonic echo, and the other to continuously capture the difference in return echo zero-crossing frequency (Doppler shift).

TI Top Device Pick

PGA460

TUSS4470

MSP430FR6047

TUSS4470

TUSS4470

TUSS4440

TUSS4470

Why Top Pick

The PGA460 was designed specifically to measure distance using ultrasonic time-of-flight. The integrated driver, receiver, ADC, and digital signal processing logic simplifies the steps required to capture this time-of-flight data.

The TUSS4470 supports the widest range of transducer frequencies from 30kHz to 1MHz to measure height from the top pointed down through air, or from the bottom pointed up through liquid.

The Texas Instruments MSP430FR604x and MSP430FR603x family of ultrasonic sensing and measurement SoCs are powerful, highly integrated microcontrollers (MCUs) that are optimized for water and heat meters.

The TUSS4470 supports the widest range of transducer frequencies from 30kHz to 1MHz to properly couple the transducer and enable this measurement through nearly all gases, liquids, or solids.

Multiple TUSS4470 devices can be easily synchronized due to the device’s ability to independently enable the receiver path regardless of the driver block’s state. This means the start of the pulse generation can be used as the sole time-of-flight origin reference for all devices.

To propagate sound waves through a solid, a large amount of sound pressure must be generated by using a transformer driver. The TUSS4440 is able to generate hundreds of volts to excite transducer, while normalizing the time-of-flight echo response regardless of the flaw dimensions.

The TUSS4470’s built-in zero-crossing feature allows the receiver to continuously monitor the incoming echo frequency. If the object is approaching the sensor, the zero-crossing frequency will increase, while an object leaving will cause the zero-crossing frequency to decease.

Recommended Evaluation Tool

BOOSTXL-PGA460

BOOSTXL-TUSS4470

EVM430-FR6047

BOOSTXL-TUSS4470

BOOSTXL-TUSS4470

BOOSTXL-TUSS4440

BOOSTXL-TUSS4470

Notes

Enable near 0mm detection by using a bi-static transducer pair for a separate transducer to generate the echo, and another transducer to capture the round-trip time-of-flight.

For top-down level sensing, use lower frequency transducers. For bottom-up level sensing, use higher frequency transducers.

TI no longer recommends using the TDC1000 for flow rate application due to known stability and accuracy issues of the device’s STOP pulse generation.

Enable one-way measurements by using a bi-static transducer pair facing each other for a separate transducer to generate the echo, and another transducer to capture the one-way time-of-flight

As transducers are added to the receiver array, the accuracy and addition details of the object to be tracked or mapped are increased.

It is important to use a contact transducer acoustic matched to the solid you are measuring the thickness of. Improper transducer face type or poor mounting will result in invalid results.

Monitoring the Doppler shift of the return echo is one method of seeking changes to the environment. Capturing the echo envelope over time per time-of-flight measurement is another way to monitor environmental changes by comparing the latest record cycle to the previous record cycle.

 

TI Ultrasonic Sensing IC Device Comparison:

 

TUSS4470

TUSS4440

PGA460

MSP430FR6047

TDC1011 / TDC1000

Device type

Analog front-end

Analog front-end

Analog front-end + digital signal processor (integrated)

Analog front-end + digital signal processor (integrated)

Analog front-end

Supported transducer frequencies

40 kHz – 1 MHz

40 – 440 kHz (pre-drive)

40 – 500 kHz

30 – 80 kHz & 180 –

480 kHz

50 kHz – 2.5 MHz

31.25 kHz – 4 MHz

Channel count

1 Channel

1 Channel

1 Channel

2 Channel

TDC1011: 1 Channel

TDC1000: 2 Channel

Drive topology

- Direct drive (max 36 V)

- Pre-drive

Transformer drive

- Transformer drive

- Direct drive with added

FETs

Direct drive (max 3.3V)

Direct drive (max 5V)

Gain stage

86 dB logarithmic amplifier

86 dB logarithmic amplifier

6 point time-varying gain

(32 to 90 dB)

Fixed gain (6.5 to 30.8 dB)

Fixed gain (20 to 41 dB)

Outputs

- Analog echo envelope

- Zero crossing

- Envelope threshold detect

- Analog echo envelope

- Zero crossing

- Envelope threshold detect

- DSP processed output (time-of-flight, amplitude, width)

- Echo data dump (down-sampled echo envelope)

- Raw digital data path (ADC, bandpass filter, rectifier, lowpass filter)

- Flow rate

- DSP processed output (time-of-flight)

- Zero crossing

- Echo start and stop pulse

Temperature sensor

No

No

On-chip temperature sensor

On-chip temperature sensor

Interface to RTD

Diagnostics

SPI diagnostics

SPI diagnostics

- System diagnostics (frequency, decay, excitation voltage)

- Supply diagnostics

(overvoltage)

Programmable

None

Automotive qualified device

N/A

N/A

PGA460-Q1

N/A

TDC1011-Q1

TDC1000-Q1

Output interface

- SPI for programming

- Analog output

- SPI for programming

- Analog output

- USART (UART + SPI)

- OWU

- TCI

- UART

- I2C

- SPI

SPI

 

The following collateral will be available on E2E until officially released to the product page:

TUSS44x0 E2E Content:

  • BOOST-TUSS44x0 EVM-GUI Overview and Quick Start Video: 

Ultrasonic FAQ Archives:

Akeem Whitehead // Texas Instruments // ASC-SENSING-CSPS // Applications Engineer
Visit our Ultrasonic Sensing FAQ page for additional information.
  • If you have any questions regarding this post or its linked content, start a new E2E discussion or thread.
    Akeem Whitehead // Texas Instruments // ASC-SENSING-CSPS // Applications Engineer
    Visit our Ultrasonic Sensing FAQ page for additional information.

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