OPA1677DBVT datasheet(25/52 Pages) TI

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9 Power Supply Recommendations

The OPA167x devices are specified for operation from 4.5 V to 36 V (±2.25 V to ±18 V); many specifications

apply from –40°C to +85°C. Parameters that can exhibit significant variance with regard to operating voltage

or temperature are shown in Section 6.8. Applications with noisy or high-impedance power supplies require

decoupling capacitors close to the device pins. In most cases, 0.1-µF capacitors are adequate.

10 Layout

10.1 Layout Guidelines

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

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

itself. Bypass capacitors are used to reduce the coupled noise by providing low-impedance power sources

local to the analog circuitry.

– Connect low-ESR, 0.1-µF ceramic bypass capacitors between each supply pin and ground, placed as

close to the device as possible. A single bypass capacitor from V+ to ground is applicable 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 usually devoted to ground planes.

A ground plane helps distribute heat and reduces electromagnetic interference (EMI) noise pickup. Physically

separate digital and analog grounds, observing 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. As shown in Figure 10-1, keeping RF and

RG close to the inverting input minimizes parasitic capacitance.

• 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.

• Cleaning the PCB following board assembly is recommended for best performance.

• Any precision integrated circuit can experience performance shifts resulting from 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.

10.1.1 Power Dissipation

The OPA167x series op amps are capable of driving 2-kΩ loads with a power-supply voltage up to ±18 V and

full operating temperature range. Internal power dissipation increases when operating at high supply voltages.

Copper leadframe construction used in the OPA167x series op amps improves heat dissipation compared to

conventional materials. Circuit board layout can also help minimize junction temperature rise. Wide copper

traces help dissipate the heat by acting as an additional heat sink. Temperature rise can be further minimized by

soldering the devices to the circuit board rather than using a socket.

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OPA1677, OPA1678, OPA1679

SBOS855D – JANUARY 2017 – REVISED DECEMBER 2021

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