Attention to good layout practices is always
recommended. For best operational performance of the device, use good PCB layout practices,
including:
- To avoid converting common-mode signals into differential signals and thermal
electromotive forces (EMFs), verify both input paths are symmetrical and well-matched for
source impedance and capacitance.
- Noise potentially propagates into analog circuitry through the power pins of the device
and of the circuit as a whole. Bypass capacitors reduce the coupled noise by providing
low-impedance power sources local to the analog circuitry.
- Connect low-ESR, 0.1µF ceramic bypass capacitors between each supply pin and ground,
placed as close as possible to the device. A single bypass capacitor from V+ to ground
is applicable for single-supply applications.
- To reduce parasitic coupling, run the input traces as far away as possible from the
supply or output traces. If these traces cannot be kept separate, crossing the sensitive
trace perpendicular is much better than in parallel with the noisy trace.
- Leakage on the DA_IN+ and DA_IN– pins potentially causes dc offset errors in the output
voltages. Additionally, excessive parasitic capacitance at these pins potentially results
in decreased phase margin and affects the stability of the output stage. If these pins are
not used to implement deliberate capacitive feedback, follow best practices to minimize
leakage and parasitic capacitance.
- Follow best practices to minimize leakage and parasitic capacitance, which includes
implementing keep-out areas in any ground planes located immediately below the
input pins.
- Minimize the number of thermal junctions. If possible, route the signal path using a
single layer without vias.
- Keep sufficient distance from major thermal energy sources (circuits with high power
dissipation). If not possible, place the device so that the thermal energy source effects
on both sides of the differential signal path are evenly matched.
- Keep the traces as short as possible.