LOW VOLTAGE ISOLATION SWITCH, IN PARTICULAR FOR A TRANSMISSION CHANNEL FOR ULTRASOUND APPLICATIONS

摘要

A low voltage isolation circuit (1) is described inserted between an input terminal (HVout) suitable for receiving a high voltage signal (IM) and an output terminal (pzt) suitable for transmitting the high voltage signal (IM) to a load (PZ) of the type comprising at least one driving block (5) inserted between a first and a second voltage reference (Vss, -Vss) and comprising a first driving transistor (Ml), inserted between the first voltage reference (Vss) and a first driving central circuit node (Xc) and a second driving transistor (M2), in turn inserted between the driving central circuit node (Xc) and the second supply voltage reference (-Vss) as well as an isolation block (8) connected to the connection terminal (pzt), to the input terminal (HVout) and, through a protection block (9) comprising a first and a second protection transistor (MD1, MD2), being in anti-series to each other and having control terminals receiving respective complementary protection driving signals (dr1, dr2), to the driving central circuit node (Xc), the isolation block (8) comprising at least one voltage limiter block (6), a diode block (7) and a control transistor (MD), in turn connected across the diode block (7) between the input (HVout) and output (pzt) terminals of the low voltage isolation switch (1) and having a control terminal (XD) connected to the driving central circuit node (Xc) through the protection block (9), said diode block (7) comprising at least one first and one second transmission diode (DN1, DN2), connected in antiparallel, i.e. by having an anode terminal of said first diode connected to a cathode terminal of said second diode and vice versa.