8.2.3 Application Curve

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

0

0.5

1

1.5

2

Time (ms)

VIN

VOUT

Figure 8-2. Input and Output Voltages of the Inverting Amplifier

8.3 Power Supply Recommendations

CAUTION

Supply voltages larger than specified in the recommended operating region can permanently

damage the device (see Section 5.1).

Place 0.1µF bypass capacitors close to the power-supply pins to reduce errors coupling in from noisy or

high-impedance power supplies. For more detailed information on bypass capacitor placement, see Section 8.4.

8.4 Layout

8.4.1 Layout Guidelines

For best operational performance of the device, use good PCB layout practices, including:

• Noise can propagate into analog circuitry through the power pins of the circuit as a whole, as well as 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-ESR, 0.1µF 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.

• To reduce parasitic coupling, run the input traces as far away from the supply or output traces as possible. If

it is not possible to keep the traces separate, it is better to cross the sensitive trace perpendicular as opposed

to in parallel with the noisy trace.

• Place the external components as close to the device as possible. Keeping RF and RG close to the inverting

input minimizes parasitic capacitance, as shown in Figure 8-3.

• 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.

LM2902-Q1, LM2902B-Q1, LM2902BA-Q1

SGLS178I – AUGUST 2003 – REVISED NOVEMBER 2024

www.ti.com

20

Submit Document Feedback

Copyright © 2024 Texas Instruments Incorporated

Product Folder Links: LM2902-Q1 LM2902B-Q1 LM2902BA-Q1