For best operational performance of the device,
use good 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 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.
- 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, 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.