The OPA593 is a high-voltage, high-current operational amplifier (op amp) applicable to a wide range of industrial and commercial applications. The device is functionally similar to low-power operational amplifiers, but with the added ability to provide upwards to 300 mA of output current while being powered by a supply voltage as high as ±42.5 V (85 V). Thermal shutdown protection, accurate current limiting, and an enable-shutdown feature allow for maximum application versatility.

This evaluation module (EVM) has been developed specifically for the OPA593, allowing users to more easily evaluate their circuit ideas and design concepts. The device has been designed for use with future HV-HI op amps similar to the OPA593 that will use the same package and pin functions and are electrically similar. Applying some imagination, the EVM PCB layout and footprints can accommodate variations on these circuit designs.

The OPA593EVM can be easily configured as a noninverting amplifier, inverting amplifier, difference amplifier, or as an improved Howland current pump (V-to-I converter) with this EVM. The user’s circuit is realized on a 13.4-cm wide × 10.8-cm long × 3.2-cm tall PCB assembly that accommodates the OPA593DNT in a 12-lead, 4-mm × 4-mm, SON (12) package. The EVM PCB top, internal and bottom copper patterns, beneath and extending outward from the package are optimized as an effective heat sink. The board design transfers heat from the op amp to the surrounding copper and then to the air, helping cool the op amp die.

The OPA593EVM is powered from either a single supply, or dual supplies with a range from ±5 V (10 V) to ±42.5 V (85 V). Adding a short wire between the two screw terminals of J7 sets up the single-supply ground, while J6 is used for V+. For dual-supply operation, use J6 (V+) for the positive connection, J7 (V–) for the negative connection, and either GND or both GND screw terminals for the ground-return connection.

A green LED illuminates when V+ is applied to ground. The OPA593 enable-shutdown function and the thermal and current flag pullup circuits are powered from two onboard, high-voltage linear regulators (TPS7A4333). The regulator output is set to 3.3 V relative to the referenced ground, or common. These onboard regulators eliminate the need for external low-voltage supplies.

The enable-shutdown function and thermal shutdown indicator are functional with either supply configuration. A yellow LED, D6, illuminates when the amplifier is set to shutdown mode (low-current, output-disabled mode). An orange LED, D7, illuminates when the OPA593 is forced into current-limit mode. The red LED, D8, illuminates when the amplifier goes into thermal shutdown. During normal OPA593 operating conditions, the D6, D7, and D8 LEDS are expected to be off.

The OPA593EVM is powered from a 10-V to 85-V single supply, or ±5-V to ±42.5-V dual supply. The external power supply used to power the EVM must be capable of supplying the total anticipated current required by the particular OPA593 circuit configuration and the load. The OPA593 can supply a dc or peak output current approaching ±300 mA. Use a power supply capable of providing at least 2x the anticipated continuous current to account for peak-current conditions. Make sure any cables used with the EVM are rated to carry the high current, and sustain voltages of 100 V or more.

The input to the EVM can be a dc source, an ac signal source such as signal generator, or the actual signal derived from a sensor or transducer. A jumper shunt can be placed across JP10 that connects a 49.9-Ω, 2-W termination resistor from the VIN+ input (J9) input to ground. This internal resistor provides a handy input instrument termination impedance very close to 50 Ω.

Other resistors on the EVM that may have to dissipate high power are laid out with the wide 2512, 2-W footprint. If the EVM is set up to use different, higher-resistance resistors, the 2-W resistors can be desoldered and removed. A 0805 footprint is incorporated within each of the larger wide 2512 resistor board patterns. These are in addition to the other 0805 footprints available for use as input and feedback resistors.

Output signals derived from the EVM can be monitored by whatever means available to the user. Often, an oscilloscope with a 10x probe provides a good way to observe the output waveform from the OPA593 output (VOUT). The output signal VOUT is connected to the J11 BNC connector that is intended for the instrument connection. Additionally, VOUT is brought to high-voltage terminal block J12. The block may be used to connect the output load to the OPA593 output. The load may be a resistor, motor, actuator, power transducer, or an active load.

Some OPA593 output loads dissipate moderate power and some may be physically large. In this case, the load can be located external to the EVM PCB.