PGA460 Ultrasonic Signal Processor and Transducer Drivers

Texas Instruments' PGA460 device is a highly-integrated system-on-chip ultrasonic transducer driver and signal conditioner with an advanced DSP core. The device has a complimentary low-side driver pair that can drive a transducer either in a transformer based topology using a step-up transformer or in a direct-drive topology using external high-side FETs. The device can receive and condition the reflected echo signal for reliable object detection. This feature is accomplished using an analog front-end (AFE) consisting of a low-noise amplifier followed by a programmable time-varying gain stage feeding into an ADC. The digitized signal is processed in the DSP core for both near-field and far-field object detection using time-varying thresholds.

The main communication with an external controller is achieved by either a time-command interface (TCI) or a one-wire USART asynchronous interface on the IO pin, or a CMOS-level USART interface on the RXD and TXD pins. The PGA460 can be put in ultra-low quiescent current low-power mode to reduce power consumption when not in use and can be woken up by commands on the communication interfaces.

The PGA460 also includes on-chip system diagnostics which monitor transducer voltage during burst, frequency, and decay time of transducer to provide information about the integrity of the excitation as well as supply-side and transceiver-side diagnostics for overvoltage, undervoltage, overcurrent, and short-circuit scenarios.

Resources

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Features

• Fully integrated solution for ultrasonic sensing
• Complimentary low-side drivers with configurable current limit supporting both transformer based and direct drive topology for transducer excitation
• Single transducer for both burst/listen or a transducer pair, one for burst and other for listen operation
• Low-noise receiver with programmable 6-point time-varying gain (32 dB to 90 dB) with DSP (BPF, demodulation) for echo envelope detection
• Two presets of 12-point time-varying threshold for object detection
• Timers to measure multiple echo distance and duration
• 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 configuration for fast initialization
• One-wire high-voltage time-command interface or USART asynchronous interface
• CMOS level USART interface
• Sensor diagnostics (decay frequency and time, excitation voltage), supply, and transceiver diagnostics