OPA211_15 Datasheet, PDF (27/45 Pages) Texas Instruments – Low Power, Precision Operational Amplifier

www.ti.com
Typical Application (continued)
9.2.3 Application Curve
20
OPA211, OPA2211
SBOS377H – OCTOBER 2006 – REVISED NOVEMBER 2015
0
-20
-40
-60
100
1k
10k
100k
1M
Frequency (Hz)
Figure 50. OPAx211 2nd-Order 25-kHz, Chebyshev, Lowpass Filter
10 Power Supply Recommendations
The OPAx211are specified for operation from 4.5 V to 36 V (±2.25 V to ±18 V); many specifications apply from
–40°C to +125°C. Parameters that can exhibit significant variance with regard to operating voltage or
temperature are presented in the Typical Characteristics.
11 Layout
11.1 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 and operational
amplifier itself. Bypass capacitors are used to reduce the coupled noise by providing low-impedance
power sources local to the analog circuitry.
– Connect low-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 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 pick-up. Make sure to physically
separate digital and analog grounds paying attention to the flow of the ground current. For more detailed
information refer to Circuit Board Layout Techniques, SLOA089.
• In order 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. As shown in Figure 51, keeping RF
and RG close to the inverting input minimizes parasitic capacitance.
• 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.
• Cleaning the PCB following board assembly is recommended for best performance.
• Any precision integrated circuit may experience performance shifts due to moisture ingress into the
plastic package. Following any aqueous PCB cleaning process, baking the PCB assembly is
recommended to remove moisture introduced into the device packaging during the cleaning process. A
Copyright © 2006–2015, Texas Instruments Incorporated
Product Folder Links: OPA211 OPA2211
Submit Documentation Feedback
27