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 the
operational amplifier individually. Use bypass
capacitors to reduce the coupled noise by
providing low-impedance power sources local to the
analog circuitry.
- Connect low-ESR, 10nF 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. For more detailed information, see also
Circuit
Board Layout Techniques.
- 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 RF and RG close to the
inverting input minimizes parasitic capacitance;
see also Section 7.4.2.
- 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.