Microchip HV738 Bedienungsanleitung

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Supertex inc.

Supertex inc.

www.supertex.com

HV738DB1

Doc.# DSDB-HV738DB1

B070114

Designing a Pulser with HV738

This demoboard data sheet describes how to use the

HV738DB1 to generate the basic high voltage pulse

waveform as an ultrasound transmitting pulser.

The HV738 circuit uses the DC coupling method in all

level translators. There are no external coupling capacitors

needed. The V

PP

and V

NN

rail voltages can be changed

rather quickly, compared to a high voltage capacitor gate

coupled driving pulser. 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 input stage of the HV738 has high-speed level

translators that are able to operate with logic signals of 1.2

to 5.0V and are optimized at 2.5 to 3.3V. In this demoboard,

the control logic signals are connected to a high-speed

ribbon cable connector. The control signal logic-high voltage

should be the same as the V

CC

voltage of the demoboard,

and the logic-low should be reference to GND.

The HV738DB1 output waveforms can be displayed by using

an oscilloscope probe directly connected to the test point

TX1~4 and GND. The soldering jumper can select whether

or not to connect the on-board equivalent-load, a 330pF,

200V capacitor, parallel with a 2.5kΩ, 1W resistor. Also, a

coaxial cable can be used to connect the user’s transducer

to easily drive and evaluate the HV738 transmitter pulser.

Typical Application Circuit

HV738 ±65V 0.75A

Ultrasound Pulser Demoboard

Introduction

The HV738 is a monolithic four channel, high speed, high

voltage, ultrasound transmitter pulser. This integrated, high

performance circuit is in a single 7x7mm, 48-lead QFN

package.

The HV738 can deliver up to ±0.75A source and sink

current to a capacitive transducer. 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.

HV738’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

over ±1.1A for pulsing, when MC0 = 1 and MC1 = 1, with

up to ±65V swings. When in mode 1, all the output stages

drop the peak current to ±140mA for low-voltage CW mode

operation to save power. Two oating 8.0VDC power

supplies, referenced to V

PP

and V

NN

, supply the P- and N-type

power FET gate drivers. This pulser waveform’s frequency

upper limit is 20MHz depending on the load capacitance.

One HV738 can also be used as four damping circuits to

generate fast return-to-zero waveforms by working with

another HV738 as four pulsing circuits. It also has built-in

under-voltage and over-temperature protection functions.

Level

Translator

V

PP

-8V

V

PF

V

DD

+8.0V

V

PP

V

NN

0 to -65V

TXN1

V

NN

+ 8V

N-Driver

1 of 4 Channels Shown

TXP1

HV

OUT

1

V

NF

V

SUB

V

LL

+2.5V+65V

V

SS

VCC

OTP

EN

MC0

MC1

PIN1

NIN1

GREF

GND

GND

Logic

Control

0V to +65V

RGND

P-Driver

HV738

Level

Translator

RGND

Produktspezifikationen