Different design techniques exist to improve creepage and clearance if deemed necessary, including adding

PBC grooves, conformal coating, and, or derating the operating voltage.

Texas Instruments offers modern packaging with small dimensions that are designed to minimize PCB area.

However, the requirement to meet any creepage or clearance specifications depends on the designer’s

interpretation and implementation of any relevant IEC or system-level standards. For more information on this

topic, visit the Demystifying Clearance and Creepage Distance for High-Voltage End Equipment document.

7.4 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.

7.5 Layout

7.5.1 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.

7.5.1.1 Thermal Considerations

Through normal operation, the op amps can self-heat. Self-heating is a natural increase in the die junction

temperature that occurs in every amplifier. This self-heating is a result of several factors, including quiescent

power consumption, package thermal resistance, PCB layout, and device operating conditions.

Operate the OPAx591 within the rated junction temperature, TJ, range to avoid thermal shutdown. Use the

Equation 5 to determine the estimated TJ

TJ=PD × RθJA+TA

(5)

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OPA591, OPA2591

SBOSA47 – FEBRUARY 2026

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