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 7-8. Current Booster Circuit

7.3 Power Supply Recommendations

The OPAx591 operates from power supplies up to ±42.5V (85V), and as little as ±4V (8V) with excellent

performance. Most behavior remains unchanged throughout the full operating voltage range, but parameters can

vary with operating voltage. A power-supply bypass capacitor of at least 0.1µF is required for proper operation.

Make sure that the capacitor voltage is rated for high voltage across the full operating temperature range. The

OPAx591 can be powered with asymmetrical supplies to optimize power dissipation in applications that do not

require an equal positive and negative output voltage swing.

7.4 Layout

7.4.1 Layout Guidelines

For best operational performance of the device, use good printed circuit board (PCB) layout practices, including

the following guidelines:

• Noise can propagate into analog circuitry through the power pins of the op amp and the circuit as a

whole. Connect low-ESR, 0.1µF ceramic bypass capacitors between each supply pin and ground. Place

the capacitors as close to the device as possible. A single bypass capacitor from V+ to ground is sufficient for

single supply applications.

• Separate grounding for analog and digital portions of circuitry is one of the simplest and most effective

methods of noise suppression. One or more layers on multilayer PCBs are typically devoted to ground

planes. A ground plane helps distribute heat and reduces EMI noise pickup. Physically separate digital and

analog grounds paying attention to the flow of the ground current.

• To reduce parasitic coupling, run the input traces as far away from the supply or output traces as possible. If

these traces cannot be kept separate, crossing the sensitive trace perpendicular is much better as opposed

to in parallel with the noisy trace.

• Place the external components as close to the device as possible.

• Keep the length of input traces as short as possible. Always remember that the input traces are the most

sensitive part of the circuit.

• Consider a driven, low-impedance guard ring around the critical traces. A guard ring can significantly reduce

leakage currents from nearby traces that are at different potentials.

• Clean the PCB following board assembly for best performance.

• Any precision integrated circuit can experience performance shifts due to moisture ingress into the plastic

package. Following any aqueous PCB cleaning process, bake the PCB assembly to remove moisture

introduced into the device packaging during the cleaning process. A low temperature, post cleaning bake

at 85°C for 30 minutes is sufficient for most circumstances.

www.ti.com

OPA591, OPA2591

SBOSA47A – FEBRUARY 2026 – REVISED SEPTEMBER 2026

Copyright © 2026 Texas Instruments Incorporated

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