OPA2277UASLASH2K5 datasheet(21/43 Pages) TI2

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8.4 Layout

8.4.1 Layout Guidelines

For best operational performance of the device, use good PCB layout practices, including:

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

amplifier 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 EMI noise pickup. Make sure to 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. As shown in Section 8.4.2, 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 due to moisture ingress into the plastic

package. Following any aqueous PCB cleaning process, baking the PCB assembly is recommended 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.

• DRM package (8-pin VSON) only: Solder the leadframe die pad to a thermal pad on the PCB. The

mechanical drawings located at the end of this data sheet list the physical dimensions for the package

and pad.

• DRM package (8-pin VSON) only: Soldering the exposed pad significantly improves board-level reliability

during temperature cycling, key push, package shear, and similar board-level tests. Even with applications

that have low-power dissipation, the exposed pad must be soldered to the PCB to provide structural integrity

and long term reliability.

8.4.1.1 DRM Package (8-Pin VSON)

The OPAx277 series uses the DRM package (also known as an 8-pin VSON), a leadless package with contacts

on only two sides of the package bottom. This near-chip-scale package maximizes board space and enhances

thermal and electrical characteristics through an exposed pad.

DRM packages are physically small, have a smaller routing area, improved thermal performance, and improved

electrical parasitics, with a pinout scheme that is consistent with other commonly-used packages, such as SOIC

and VSSOP. Additionally, the absence of external leads eliminates bent-lead issues.

The DRM package can be easily mounted using standard printed-circuit-board (PCB) assembly techniques. See

the QFN/SON PCB Attachment and Quad Flatpack No-Lead Logic Packages application notes, both available

for download at www.ti.com.

The exposed leadframe die pad on the bottom of the package must be connected to V–.

www.ti.com

OPA277, OPA2277, OPA4277

SBOS079C – MARCH 1999 – REVISED FEBRUARY 2023

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Product Folder Links: OPA277 OPA2277 OPA4277

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