7.2.4 Current Booster

Some instances exists where designers require more output current drive from the OPAx591. Fig shows a

simple current booster circuit that enables high voltage, high current drive capability. The circuit can be built

with a couple of power MOSFETs or BJTs. One advantage of this circuit over monolithic power amplifiers is the

significantly better thermal performance. The external transistors deliver the power and the OPAx591 is kept

relatively cool to prevent any thermally related performance degradation.

+

–

1k

7k

OPAx591

VIN

85V

10

400pF

200

200

V+

V

CL

RL

VOUT

Figure 7-7. Current Booster Circuit

7.3 Creepage and Clearance

When designing and building electrical systems with high voltage, two important concepts to consider are

creepage and clearance. Creepage distance refers to the shortest path that an electric current can take along

the surface of an insulating material, such as a printed circuit board (PCB) or a plastic enclosure. Clearance

distance refers to the shortest distance between two conductive parts, such as wires, terminals, or components,

through the air. Figure 7-8 illustrates creepage and clearance for a typical integrated circuit (IC).

```

PCB

Integrated Circuit

Creepage distance

Clearance distance

Groove

Creepage

Integrated Circuit

PCB

High

Voltage

PCB trace

Potentially

Low Voltage

PCB Trace

Creep

age

High

Voltage

Differentia

l Between

V+ and

V

Top view

Edge View

Creepage

and

Clearance

Figure 7-8. Creepage and Clearance in Integrated Circuits

Several standards exist with creepage and clearance guidance, but how the standards pertain to operational

amplifiers and other integrated circuits is largely left to interpretation and internal requirements. The guidance

distances are significantly affected by pollution degree, maximum voltage, and the underlying application. In

the case of creepage, the comparative tracking index (CTI) rating of the insulating material is a major factor.

OPA591, OPA2591

SBOSA47 – FEBRUARY 2026

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