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TI PGA460超声信号处理和傳感器驱动器解決方案

TI公司的PGA460是高度集成的片上系统(SoC),具有先进DSP核的傳感器驱动器和信号调理器.器件有一个互补低边驱动器对,能采用升压变压器驱动基于变压器拓扑的傳感器,或在直接驱动拓扑中采用外接高边FET驱动傳感器.器件能接收和调理反射回声信号,以用于可靠的物体检测.这种特性是采用由低噪音放大器和可编时变增益级的ADC组成的模拟前端(AFE)来实现的.数字化信号采用时变阈值在DSP核中进行处理,适用于近场和远场物体检测.低噪音接收器有可编程6点时变增益(32-90dB),DSP(BPF,解调器)用来回声包络检测.两个预设的12点时变阈值用来物体检测,而计时器用来测量多个回声距离和持续时间.PGA460输出驱动器包括互补低边驱动器,能驱动中心抽头变压器,以便在超声傳感器上产生高的激励电压,获得所需的声压值(SPL).输出驱动器还能配置成用在直接驱动模式,能实现可配置的电流限制,以提高变压器驱动效率,可配置突发频率和突发长度,以变和大多数傳感器兼容.主要用在超声波雷达,物距和位置检测,压力和接近检测,無人機和機器人着陆辅助和障碍物检测,占用和运动传感.本文介绍了PGA460主要特性,框图,回声产生框图和变压器驱动与直接驱动电路图,評估板PGA460PSM-EVM主要特性和框图,电路图,材料清单和PCB布局图.

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.

PGA460主要特性:

• 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.

PGA460應用:

• Ultrasonic Radar
• Object distance and Position Sensing
• Presence and Proximity Detection
• Drone and Robotics Landing Assist and ObstacleDetection
• Occupancy and Motion Sensors

圖1.PGA460功能框圖

圖2.PGA460回聲産生框圖

圖3.PGA460典型應用框圖(變壓器驅動)

圖4.PGA460模擬前端

圖5.PGA460變壓器驅動電路圖

圖6.PGA460直接驅動電路圖

評估板PGA460PSM-EVM

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.

評估板PGA460PSM-EVM主要特性:

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

图7.評估板PGA460PSM-EVM框图
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.

图8.带软件调整的評估板PGA460PSM-EVM建立图

图9.評估板PGA460PSM-EVM电路图
評估板PGA460PSM-EVM材料清单:


图10.評估板PGA460PSM-EVM PCB布局和元件放置图
詳情請見:
http://www.ti.com/lit/ds/slasej4b/slasej4b.pdf
和http://www.ti.com/lit/ug/slau817/slau817.pdf
以及http://www.ti.com/lit/ug/slau659b/slau659b.pdf
slau817.pdf
slasej4b.pdf
slau659b.pdf

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