Microchip MD2131DB1

Description

This MD2131DB1 datasheet describes how the demoboard is to used to generate the ultrasound transmit beamforming waveform with the Gaussian profile, and the adjustable frequency,amplitude and phase angle. It also provides information about how to design a user application circuit and PCB using the Supertex MD2131 and DN2625 devices.

The MD2131DB1 circuit uses two depletion-mode MOSFETs in the push-pull mode to drive the center tapped, wide band, ultrasound output transformer. The two depletion-mode MOSFETs are packaged in a single 5x5mm DFN package.The sources of the MOSFETs are directly driven by theMD2131’s two outputs, whose maximum peak sinking current is up to 3.0A. These current source outputs are controlled by the MD2131’s internal angular vector switch matrix and the in-phase and quadrature PWM input signals.

All of the MD2131’s logic control signals are generated by two small CPLD programmable logic circuits clocked by an on-board 160MHz crystal oscillator. The CPLD circuits not only generate accurate timing for the high speed PWM control waveforms, but also the serial data and clock to set and change the waveform amplitude DAC and phase angle data registers. The external clock input can be used if the on-board oscillator is disabled. The external trigger input can be used to synchronize the burst waveforms’ launch timing. There are five push buttons for enabling and selecting the output wave-form frequency, phase angle and amplitude. Four color LEDsindicate the power, chip enable and wave-form parameter selection states. The MD2131DB1 output waveform can be displayed by using an oscilloscope and the high impedance probe at the TP13 test point. It also can use an SMA to BNC, 50Ω, coaxial cable to directly connect to an oscilloscope, with an attenuation of 5:1 if R10 is 200Ω. A cable can also be used to directly drive the user’s transducer. Jumper J4 can be used to select whether or not to connect the on-board equivalent load, which is formed by a 220pF capacitor in parallel with a 1.0kΩ resistor.

More information

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