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Supertex公司的HV7355是八路單極高壓高速超聲波脈沖發生器,輸出電壓0V-150V,源和沉電流為±1.5A,連續波模式±300mA,高達18MHz工作頻率,2.5V-3.3V CMOS邏輯接口,主要用在手提超聲波圖像儀,壓電傳感器驅動器,NDT超聲波發送器和脈沖波形發生器.本文介紹了HV7355主要特性, 典型應用電路以及150V/1.5A單極超聲波脈沖器演示板HV7355DB1主要特性, 方框圖和電路圖.

Eight Channel, High Speed, Unipolar, Ultrasound Pulser 1.5A 150V

The Supertex HV7355 is an eight-channel, unipolar, high voltage, high-speed pulse generator. It is designed for medical ultrasound applications. This high voltage and high speed integrated circuit can also be used for other piezoelectric, capacitive or MEMS sensors in ultrasonic nondestructive detection and sonar ranger applications.

The HV7355 consists of a controller logic interface circuit, level translators, MOSFET gate drivers and high current P-channel and N-channel MOSFETs as the output stage for each channel.

The output stages of each channel are designed to provide peak output currents over ±1.5A for pulsing, when MC = 1, with up to 150V swings. When MC = 0, all the output stages drop the peak current to ±500mA for low-voltage CW mode operation to save power. This direct coupling topology of the gate driver not only saves one high voltage capacitor per channel, but also makes the PCB layout easier.

HV7355主要特性:

?? HVCMOS technology for high performance

?? High density integrated ultrasound transmitter

?? 0 to +150V output voltage

?? ±1.5A source and sink current (min.)

?? ±300mA current in CW mode

?? Up to 18MHz operating frequency

?? Matched delay times

?? Built-in gate driver floating voltage regulator

?? 2.5 to 3.3V CMOS logic interface

HV7355應用:

?? Portable medical ultrasound imaging

?? Piezoelectric transducer drivers

?? NDT ultrasound transmission

?? Pulse waveform generator
 

圖1.HV7355典型應用電路

150V/1.5A單極超聲波脈沖器演示板HV7355DB1

150V, 1.5A, Unipolar Ultrasound Pulser Demoboard

The HV7355 is a monolithic eight-channel, high-speed,high voltage, unipolar ultrasound transmitter pulser. This integrated, high performance circuit is in a single, 8x8x0.9mm, 56-lead QFN package.

The HV7355 can deliver guaranteed ±1.5A source and sink current to a capacitive transducer with 0 to +150V peak voltage. It is designed for medical ultrasound imaging and ultrasound material NDT applications. It can also be used as a high voltage driver for other piezoelectric or capacitive MEMS transducers, or for ATE systems and pulse signal generators as a signal source.

The HV7355’s circuitry consists of controller logic circuits, level translators, gate driving buffers and a high current and high voltage MOSFET output stage. The output stages of each channel are designed to provide peak output currents typically over ±1.5A for pulsing, with up to 150V swings. The upper limit frequency of the pulser waveform is dependent upon the load capacitance. With different capacitance load conditions the maximum output frequency is about 20MHz.

This demoboard datasheet describes how to use the HV7355DB1 to generate the basic high voltage pulse waveform as an ultrasound transmitting pulser.

The HV7355 circuit uses DC-coupling from a 3.3V logic input to output TX0~7 internally, therefore the chip needs three sets of voltage supply rails: VLL (+3.3V), VDD/VSS (+/-5.0V) and VPP (up to +150V). The VPP high voltage supply can be changed rather quickly, compared to the capacitor gatecoupled driving pulsers. This direct coupling topology of the gate drivers not only saves two high voltage capacitors per channel, but also makes the PCB layout easier.

The control signal logic-high voltage should be the same as the VLL voltage of the IC, and the logic-low should be referenced to GND.

The HV7355DB1 output waveforms can be displayed using an oscilloscope by connecting the scope probe to the test points TX0~7 and GND. The soldering jumper can select whether or not to connect the on-board dummy load, a 330pF capacitor paralleling with a 2.5kΩ resistor. The test points can be used to connect the user’s transducer to easily evaluate the pulser.
 

圖2.演示板HV7355DB1方框圖


圖3.演示板HV7355DB1電路圖


圖4.演示板HV7355DB1外形圖