MD0107

Supertex inc. Quad High Voltage, Auto Damping Device Features ►► ►► ►► ►► Up to ±130V input voltage protection 35Ω typical ON resistance Fast switching speed No external supplies needed MD0107 General Description Applications ►► ►► ►► ►► ►► Medical ultrasound imaging NDT applications Fast resettable fuses High side switches Data acquisition The MD0107 can be considered as a normally closed switch with a typical switch resistance of 35Ω. In this state, the MD0107 ensures that any leakage currents are shunted to ground, while maintaining a low voltage drop. This low voltage level is beneficial as it ensures that the anti-parallel diodes in the transmit path remain off during the receive cycle of the system. Thus the anti-parallel diodes more effectively block the small signals and prevent transmitter noise from contaminating the receive signal.   During operation of the pulser, the MD0107 switch opens and thus presents a high impedance to the transmitter pulse. The switch opens as soon as the voltage across it exceeds +/-2V and can withstand up to +/-130V. In this off-state, the MD0107 has very little effect on the transmit pulses or the power dissipated by the pulser.   The impedance of the MD0107, when the voltage across it is low, is suitable for terminating transmission lines. Where the line impedance is higher than the nominal 35Ω of the MD0107, a series resistor can be added; for example terminating a ~75Ω line can be effectively achieved by adding a 39Ω resistor. Wi...