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 connections of the board and propagate to the power pins of the op amp itself. Bypass capacitors are used to reduce the coupled noise by providing a low-impedance path to ground.
- Connect low-ESR, 0.1µF ceramic bypass capacitors
between each supply pin and ground, placed as
close to the device as possible. One bypass
capacitor from V+ to ground is adequate 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. Take care 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 at a 90 degree angle is much better as opposed to running the traces in parallel with the noisy trace.
- Place the external components as close to the
device as possible, as shown in Layout Example. Keeping R1
and R2 close to the inverting input
minimizes parasitic capacitance.
- Keep the length of input traces as short as possible. 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.
- TI recommends cleaning the PCB following board assembly 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, TI recommends baking 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.