SBOU268 November 2021 OPA593
The OPA593 op amp and other OPA593EVM components are protected from accidental supply reversal by the inclusion of series-connected Schottky diodes directly after the power supply jacks. These diodes exhibit a small forward-voltage drop; therefore, when setting the OPA593EVM external supply voltages, the levels must be increased slightly to accommodate the diode voltage drops. The supply voltages can be monitored at the VDD (TP17) and VSS (TP19) test points that are placed after the Schottky protection diodes. TP18 is the common for these two test points.
High-current op amps such as the OPA593 are used to drive a load that presents a complex load impedance (ZL = R±jX) at the output. If this complex impedance has significant inductive reactance, the inductance can produce a back electromotive force (EMF) voltage that could potentially damage the OPA593 output stage. The OPA593EVM has ultra-fast rectifier diodes D3 and D4 connected from the output pin to the PCB internal VDD and VSS supply lines that help provide back EMF protection. The diodes act as voltage clamps helping protect the output transistors from potential high-voltage occurrences that might occur during a back EMF event.