The PGA460 device is a highly-integrated system onchipultrasonic transducer driver and signalconditioner with an advanced DSP core. The devicehas a complimentary low-side driver pair that candrive a transducer either in a transformer basedtopology using a step-up transformer or in a directdrivetopology using external high-side FETs. Thedevice can receive and condition the reflected echosignal for reliable object detection. This feature isaccomplished using an analog front-end (AFE)consisting of a low-noise amplifier followed by aprogrammable time-varying gain stage feeding intoan ADC. The digitized signal is processed in the DSPcore for both near-field and far-field object detectionusing time-varying thresholds.
The main communication with an external controller isachieved by either a time-command interface (TCI) ora one-wire USART asynchronous interface on the IOpin, or a CMOS-level USART interface on the RXDand TXD pins. The PGA460 can be put in ultra-lowquiescent current low-power mode to reduce powerconsumption when not in use and can be woken upby commands on the communication interfaces.
The PGA460 also includes on-chip systemdiagnostics which monitor transducer voltage duringburst, frequency and decay time of transducer toprovide information about the integrity of theexcitation as well as supply-side and transceiver-sidediagnostics for overvoltage, undervoltage, overcurrentand short-circuit scenarios.
The PGA460 device is a signal-conditioning and transducer-driver device for ultrasonic sensing for object ordistance sensing. The output driver consists of complimentary low-side drivers capable of driving a center-taptransformer to generate large excitation voltages across an ultrasonic transducer and as a result create thedesired sound pressure level (SPL). The output driver can also be configured to be used in direct-drive modewithout a transformer using external FETs. The output driver implements configurable current limit for efficientdriving of the transformer and configurable bursting frequencies and burst length to be compatible with a largenumber of transducers.
The analog front-end (AFE) can sense the received echo from the transducer and amplify it for correct objectdetection. The AFE implements a low-noise amplifier followed by a time-varying gain amplifier that allows signalsfrom objects at a variable distance to be amplified correspondingly. This implementation allows for the maximumdynamic range of the ADC to be used for both near-field and far-field objects in the same recording. Anembedded temperature sensor can be used to calibrate the signal conditioner for changes in temperature. Thedigital signal processing path further filters the received echo and uses time-varying thresholds for accuratedetection of objects. Two presets for both bursting and thresholds are available which allow faster detectioncycles by saving time required to configure the device between multiple bursts. Most configuration parameters are stored in nonvolatile memory for quick power up, which reduces initialization time.
The PGA460 device provides multiple IO protocols to communicate with the master controller. The deviceprovides a time-command interface and one-wire UART on the VPWR reference IO pin. It also provides bothsynchronous and asynchronous USART on the TXD, RXD, and SCLK pins.
• Fully Integrated Solution for Ultrasonic Sensing
• Complimentary Low-Side Drivers WithConfigurable Current Limit Supporting Both Transformer Based and Direct Drive Topology forTransducer Excitation
• Single Transducer for Both Burst/Listen or aTransducer Pair, One for Burst and the Other forListen Operation
• Low-Noise Receiver With Programmable 6-PointTime-Varying Gain (32 to 90 dB) With DSP (BPF,Demodulation) for Echo Envelope Detection
• Two Presets of 12-Point Time-Varying Thresholdfor Object Detection
• Timers to Measure Multiple Echo Distance andDuration
• Integrated Temperature Sensor
• Record Time for Object Detection up to 11 m
• 128 Bytes of RAM for Echo Recording
• 42 Bytes of User EEPROM to Store Configurationfor Fast Initialization
• One-Wire High-Voltage Time-Command Interfaceor USART Asynchronous Interface
• CMOS Level USART Interface
• Sensor Diagnostics (Decay Frequency and Time,Excitation Voltage), Supply, and TransceiverDiagnostics.
• Ultrasonic Radar
• Object distance and Position Sensing
• Presence and Proximity Detection
• Drone and Robotics Landing Assist and ObstacleDetection
• Occupancy and Motion Sensors
The PGA460PSM-EVM allows users to evaluate the functionality of Texas Instrument’s PGA460-Q1ultrasonic sensor-signal conditioner IC. The PGA460-Q1 is a fully integrated system-on-chip, analog frontend(AFE) device for ultrasonic sensing. This user’s guide describes both the hardware platformcontaining a sample PGA460-Q1 device and the graphical user interface (GUI) software used to configurethe functionality and diagnostics. In addition to evaluating the PGA460-Q1 device, the other objective ofthis board is to display the ultrasonic echo profile and measurement results of a transformer driven closedtoptransducer when using the GUI.
The PGA460PSM-EVM is a fully assembled evaluation module (EVM) designed for the combinedevaluation of the PGA460-Q1 ultrasonic-sensor signal conditioner IC, an ultrasonic transducer, and centertaptransformer. The user can evaluate any two-pin, open or closed-top, ultrasonic transducer in theoperating frequency range of 30 to 80 kHz or 180 to 480 kHz.
The PGA460-Q1 EVM’s MSP430F5529 LaunchPad™ Development Kit (MSP-EXP430F5529LP) is usedas an example USB-to-PC GUI communication bridge as an example on how to implement a master MCUto communicate with the PGA460-Q1 through USART or IO interfaces.
The MSP-EXP430F5529LP is controlled by commands received from the PGA460-Q1 EVM GUI, andreturns data to the GUI for display and further analysis.
The PGA460PSM-EVM incorporates the minimum circuitry and components with the following features:
• PGA460-Q1 ultrasonic sensor signal conditioner IC
• Ultrasonic closed-top transducer
• Center-tap push-pull transformer
The following elements are required for full evaluation of the PGA460PSM-EVM:
• MSP-EXP430F5529LP for USART (UART and SPI) communication
• PGA460-Q1 EVM GUI (download from PGA460-Q1 product page)
• A computer with Windows 7 or later,and .NET Framework 4.5
• Micro-USB to USB cable (included with the purchase of the PGA460-F5529-BNDL)
• (Optional) BOOSTXL-PGA460 BoosterPack (included with the purchase of the PGA460-F5529-BNDL)for One-Wire Interface communication
• (Optional) A single power supply unit, battery, or AC/DC adapter to provide a voltage output from 6 Vto 28 V, and a current output up to 500 mA.