V-

OUTPUT

GND

GND

GND

18

OPAX607

SBOS981B – OCTOBER 2019 – REVISED FEBRUARY 2020

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10 Power Supply Recommendations

The OPAX607 is specified for operation from 2.2 V to 5.5 V (±1.1 V to ±2.75 V), applicable from –40°C to

+125°C. Place 0.1-µF bypass capacitors close to the power-supply pins to reduce errors coupling in from noisy

or high-impedance power supplies.

CAUTION

Supply voltages larger than 6 V can permanently damage the device (see the Absolute

Maximum Ratings table).

For more detailed information on bypass capacitor placement, see the Layout Guidelines section.

11 Layout

11.1 Layout Guidelines

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-supply pins of the circuit as a whole and of

the operational amplifier. Bypass capacitors are used to reduce the coupled noise by providing low-

impedance power sources local to the analog circuitry.

–

Connect low-equivalent series resistance (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 the 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. 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 perpendicularly is much

better than crossing in parallel with the noisy trace.

•

inverting input minimizes parasitic capacitance; see Figure 12 and Figure 13.

•

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.

11.2 Layout Examples

Figure 12. Operational Amplifier Board Layout for a Noninverting Configuration