1 HV732DB1 the hv732 is a complete, high-speed, high voltage, ultrasound transmitter pulser. this integrated high performance circuit is in a single 7x7x0.9mm 44-lead, multi-die, qfn package. the hv732 can deliver up to 2a source and sink current to a capacitive transducer. it is designed to be used as a high voltage pulser or transmitter in medical ultrasound imaging and ultrasound material ndt applications. it can also be used for other piezoelectric or capacitive mems transducers as a high voltage driver, or for ate systems and pulse signal generators as a signal source. the hv732 has built-in damping circuits to generate fast return-to-zero waveforms. it also has built-in, high voltage mosfet gate-clamping functions to quickly change the output waveform amplitude. hv732 circuitry consists of controller logic circuits, level translators, a mosfet driving buffer, gate-clamp circuits and mosfet transistors as the high current and high voltage output stage. there are two pairs of mosfets in the output stage. each pair is consists of a p-channel and an n-channel mosfet. in each pair of mosfets, the p-fet and n-fet are designed to have the same impedance and can provide peak currents of over 2 amps. in the mosfet gate-driver circuits, the output of the driver can swing from 0 to 9v~12v on p dr and n dr pins, and the p-channel damping output swings from 0v to C5v on the dmpo pin. hv732 can generate 100v nrz, rz and pw pulses and low voltage cw waveforms. the up frequency limit of this ic is as high as 35mhz to 40mhz dependent on the load capacitance. designing a pulser with hv732 this demo board data sheet describes how to use the HV732DB1 to generate the basic high voltage pulses for an ultrasound transmitter with a rtz feature. the hv732 circuit uses the capacitor-coupling method in its level translators, except for the one driving the n-channel damping mosfet, which is dc coupled. there are three 10nf 200v ceramic capacitors connecting the driver output to the mosfets gate for the coupling purposes. the input stage of the hv732 has high-speed level translators that are able to operate with logic signals of 1.8v, 2.5v or 3.3v. in this demo board, the control logic signals are connected to a high-speed ribbon cable connector. the control signal logic-high voltage should be same as the v cc voltage of the demo board, and the logic-low should be referenced to gnd. the HV732DB1 output waveforms can be displayed using an oscilloscope directly by connecting the scope probe to the test point hv out and gnd. the soldering jumper r1 can select whether or not to connect the on-board equivalent- load, a 220pf, 200v capacitor, parallel with a 1k, 1w resistor. a coaxial cable can also be used to connect the users transducer to be driven and evaluated with this hv732 transmitter pulser directly and easily. logic control 0 to -100v hv out c l r l 1k 220pf hv out supertex s u p e r t e x hv732 h v 7 3 2 rgnd p rgnd n out p out n tx n tx p v pp v sub p gate p dr v dd av dd v ll en p in n in damp clamp v ln agnd gnd n dr n gate dmpo dmpi v nn -5.0v 0 to -100v +100v +9.0v to 12v +1.8v to 3.3v schematic block diagram high speed 100v 2a integrated ultrasound pulser demo board introduction free datasheet http:///
2 HV732DB1 the pcb layout techniques the big thermal pad at the bottom of the hv732 package is connected to the v sub pin to make sure that in any condition it always has the highest potential of the chip. v sub is the connection of the ics substrate. the other two smaller pieces of the slab at the bottom of the chip are the drains of the high voltage output p-channel and n-channel mosfets. they are connected to high voltage outputs. pcb designers need to pay attention to the connecting the traces as high-voltage and high-speed traces. in particular, low capacitance to the ground plane and more trace spacing needs to be applied in this situation. high-speed pcb trace design practices that are compatible with about 50mhz to 100mhz operating speed are used for the demo board pcb layout. the internal circuitry of the hv732 can operate at a quite high frequency, with the primary speed limitation being load capacitance. because of this high speed and the high transient currents that result when driving capacitive loads, the supply voltage bypass capacitors and the driver to the fets gate-coupling capacitors should be as close to the pins as possible. the gnd and agnd pin pads should have low inductance feed-through connections that are connected directly to a solid ground plane. the v pp and v nn supplies can draw fast transient currents of up to 2.0a, so they should be provided with a low-impedance bypass capacitor at the chips pins. a ceramic capacitor of 0.47f to 1.0f may be used. minimize the trace length to the ground plane, and insert a ferrite bead in the power supply lead to the capacitor to prevent resonance in the power supply lines. for applications that are sensitive to jitter and noise and are using multiple hv732 ics, insert another ferrite bead between v dd and decouple each chip supply separately. pay particular attention to minimizing trace lengths and using suf? cient trace width to reduce inductance. surface mount components are highly recommended. since the output impedance of hv732s high voltage power stages are very low, in some cases it may be desirable to add a small value resistor in series with the output tx p and tx n to obtain better waveform integrity at the load terminals. this will, of course, reduce the output voltage slew rate at the terminals of a capacitive load. the same technique can be applied to the driver output to p gate and n gate , if necessary. be aware of the parasitic coupling from the outputs to the input signal terminals of hv732. this feedback may cause oscillations or spurious waveform shapes on the edges of signal transitions. since the input operates with signals down to 1.8v, even small coupling voltages may cause problems. use of a solid ground plane and good power and signal layout practices will prevent this problem. also ensure that the circulating ground return current from a capacitive load cannot react with common inductance to create noise voltages in the input logic circuitry. testing the integrated pulser this hv732 pulser demo board should be powered up with multiple lab dc power supplies with current limiting functions. the following power supply voltages and current limits have been used in the testing: v sub / v pp = +15v to +100v 2.0ma, v nn = 0v to -100v 2.0ma, v dd = +9v to +12v 10ma, v ln = -5v 5.0ma. v cc = +3.3v 5.0ma. v sub and v pp generally need to be connected to the same voltage. if the v cc current needs to be included in the v cc current of the users logic circuits, then a higher current limit should be set. the power-up or down sequences of the voltage supply ensure that the hv732 chip substrate, v sub and v pp , are always at the highest potential of all the voltages supplied to the ic. the on-board dummy load 220pf/1k should be connected to the high voltage pulser output through the solder jumper when using an oscilloscope high impedance probe to meet the typical loading conditions. for looking into the different loading conditions, one may change the values of rc within the current and power limit of the device. in order to drive piezo transducers with a cable, one should match the output load impendence properly to avoid cable and large transducer re? ections. a 70 to 75 coaxial cable is recommended. the coaxial cable end should be soldered to the hv out and gnd directly with very short wire length leads. all the on-board test points are designed to work with the high impedance probe of the oscilloscope. some probes may have limited input voltage. when using the probe on these high voltage test-points, make sure that v pp /v nn does not exceed the probe limit. using the high impendence oscilloscope probe for the on-board test points, it is important that the ground leads to the circuit board ground plane are as short as possible. there are examples of the hv732 output waveforms and pulser input shown in the diagrams on pages 5-8. precautions need be applied to not overlap the logic-high time periods of the control signals. permanent damage to the device may occur when cross-conduction or shoot- through currents exceed the device maximum limits. the input logic pins should connect to the low impedance cmos logic control circuit outputs or 1k pull-up or pull-down resistors during the test. leave these pins ? oating or logic state unknown may damage the device. free datasheet http:///
3 HV732DB1 circuit schematic r6 10 v dd tp16 r7 10 tp8 tp20 tp13 tp21 tp14 v pp v cc c3 0.22 tp15 2 4 6 8 10 1 3 5 7 9 j1 header 5x2 tp3 v cc = +1.8 to +3.3v v sub v cc v nn c7 1u 100v tp12 v ln c4 0.22 c11 10n 200v p in v dd n in damp 3 1 2 d2 bav99 v pp tx n v ln v nn 3 1 2 d1 bav99 clamp c12 1u 100v 4 3 d4b c5 10n 200v tp19 v cc v pp v cc v ln v dd tp5 tp6 v nn c6 1u 100v v pp out p 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 tp10 2 1 d5 tp17 out n 1 2 3 4 5 6 7 8 j2 header 8 v cc c8 220p 250v tp1 hv out tp18 v ln = -5v r2 1k 1w v dd = +9.0 to +12v 4 3 d3b en r8 10 v sub v dd tp9 v nn = 0 to -100v 1 6 d3a bat54dw-7 tp4 c1 0.22 2 1 d6 b1100-13 v sub /v pp = +15 to +100v 1 6 d4a tx p c9 0.22 r1 0 r3 1 r4 10 v dd tp11 c2 0.22 2 1 d7 tp2 r5 10 tp7 dmpo gnd n dr v dd v dd v sub rgnd n out n n gate v nn v nn v nn v nn v nn tx n tx n nc tx p tx p v pp v pp v pp v pp v pp p gate out p rgnd p v sub v dd v dd p dr gnd gnd dmpi p in v ln av dd agnd v sub en damp clamp v ll n in v sub tx n tx p u1 hv732 c10 10n 200v pcb layout free datasheet http:///
4 HV732DB1 board voltage supply power-up sequence connector and test pin description logic control signal input connector 1v cc logic-high reference voltage supply v ll , +1.8v to 3.3v 2 en pulser output enable logic signal input, active high 3 gnd logic signal ground, 0v (3) 4p in pulser positive high voltage pulse output control logic signal input, active high. (2) 5 gnd logic signal ground, 0v (3) 6n in pulser negative high voltage pulse output control logic signal input, active high. (2) 7 gnd logic signal ground, 0v (3) 8 damp pulser high voltage pulse output zero-damping control logic signal input, active high. (2) 9 gnd logic signal ground, 0v (3) 10 clamp output stage p and n-mosfets gate-clamping control logic signal input, active high. (2) power supply connector 1v cc logic-high reference voltage supply, +1.8v to 3.3v.with current limit to 5.0ma 2 gnd low voltage power supply ground, 0v 3v ln -5v negative bias supply with current limit to 5.0ma 4v dd +9v to 12v positive driver voltage supply with current limit to 10ma 5v nn 0v to -100v negative high voltage supply with current limit to 2.0ma (4) 6 gnd high voltage power supply ground, 0v 7v pp +15v to +100v positive high voltage supply with current limit to 2.0ma (4) 8v sub chip substrate bias voltage, must be same as v pp with current limit to 2.0ma (4) 1v cc +15v to +100v the substrate and positive high voltages (1) 2v dd +9v to +12v positive drive supply voltage 3v sub /v pp +1.8v to 3.3v positive logic supply voltage 4v ln -5v negative bias supply voltage 5v nn 0v to +/-100v negative high voltage (1) 6 logic active any logic control active high signals note: (1) turn on or off with v sub /v pp = +25v, v nn = -25v is recommend. then ramp v pp or v nn up or down slowly if without clamp control signal is hi. v sub /v pp = +100v and v nn = -100v are maximum. (2) overlap control signal logic-high periods may cause the device permanent damage (3) due to the high speed control signal, every gnd wire in the ribbon cable need connect to signal ground. (4) it is important to note that some the high voltage capacitors and diodes on board are only rated at 100v, if need test uni polar conditions like v sub /v pp = +150v and v nn = -50v, or v sub /v pp = +200v and v nn = 0v etc., their voltage ratings need to be upgraded. free datasheet http:///
5 HV732DB1 input and output waveform examples free datasheet http:///
6 HV732DB1 note: the duty cycle of cw or pw burst is set to about 0.1% for the power dissipation limit of the load resistor. input and output waveform examples (cont.) free datasheet http:///
7 HV732DB1 0 200 400 600 800 100012001400160018002000 hv732-db1 waveform with 220pf//1k load ns 50v/div 5v/div p in n in damp h out 0 100 200 300 400 500 600 700 800 900 1000 hv732-db1 waveform a with 220pf//1k load ns 50v/div 5v/div p in n in damp h out 0 100 200 300 400 500 600 700 800 900 1000 hv732-db1 waveform b with 220pf//1k load ns 50v/div 5v/div p in n in damp h out 0 100 200 300 400 500 600 700 800 900 1000 hv732-db1 waveform c with 220pf//1k load ns 50v/div 5v/div p in n in damp h out 0 100 200 300 400 500 600 700 800 900 1000 hv732-db1 waveform d with 220pf//1k load ns 50v/div 5v/div p in n in damp h out 0 100 200 300 400 500 600 700 800 900 1000 hv732-db1 waveform e with 220pf//1k load ns 50v/div 5v/div p in n in damp h out pulser oscilloscope waveforms free datasheet http:///
8 HV732DB1 0 100 200 300 400 500 600 700 800 900 1000 hv732-db1 waveform c at 20mhz,220pf//1k ns 50v/div 5v/div p in n in damp h out 0 100 200 300 400 500 600 700 800 900 1000 hv732-db1 waveform c at 10mhz,220pf//1k ns 50v/div 5v/div p in n in damp h out 02468101214161820 hv732-db1 waveform c 625khz 220pf/1k us 50v/div 5v/div p in n in damp h out 081507 pulser oscilloscope waveforms (cont.) free datasheet http:///
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