AN3240

STHV748 PCB demo description

Doc ID 17689 Rev 1

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STHV748 PCB demo description

The STHV748 PCB demo can drive four transducers as 4-channel transmitters/receivers for

ultrasound and other applications. The demo board consists of one STHV748 in a 64-lead

9x9x1 mm QFN package.

The STHV748 can deliver up to a ±2.0 A source and sink current to a capacitive transducer.

It is designed for medical ultrasound imaging and ultrasound material NDT applications.

The STHV748 output waveforms can be displayed directly for each channel Ch A/B/C/D

using an oscilloscope by connecting the scope probe to the J1, J2, J3, and J4 jumpers,

moreover, the user can select whether or not to connect the onboard equivalent load, a 300

pF 200 V capacitor paralleled with a 100

Ω, 2 W resistor (or alternatively, 200 Ω//50 pF -

200

Ω//250 pF - no-load). A coaxial cable can also be used to easily connect the user

transducer.

IN1/2/3/4, for each channel available in IC, is controlled via the 13 pins of the C1 (CONN1)

head connector on the board (34 pins).

The main issues in this PCB design are the capacitance values, to ensure good filtering and

an effective decoupling between the low voltage inputs (IN1, IN2, IN3, IN4, and EN for each

channel) and the HV switching signals (XDCR, HVOUT, etc.,) which is ensured by the layer

separation used.