Microchip MD2130DB2

Description

This demoboard data sheet describes how to use the MD2130DB2 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 andPCB using the MD2130 and DN2625 devices.

The MD2130DB2 circuit uses two depletion mode, high voltage, DN2625 MOSFETs in the push-pull mode to drive the center-tap wideband ultrasound output transformer. The MOSFETs are in a DK6 surface mount package. The sources of the MOSFETs are directly driven by MD2130’stwo outputs, whose maximum peak sinking current is up to 3A. These current-source outputs are controlled by the MD1230’s internal angular vector switch matrix and the inphase and quadrature PWM input signals.

All of the MD2130’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 andchange the waveform amplitude DAC and phase angle data registers. The external clock input can be used if the onboard 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 theoutput waveform frequency, phase angle and amplitude.Four color LEDs indicate the power, chip enable and waveform parameter selection states.The MD2130DB2 output waveform can be displayed by using an ocilloscope and the high impedance probe at the TP13 test point. It also canuse 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 a220pF capacitor in parallel with a 1kΩ resistor.

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