OPA180_15 Datasheet, PDF (14/38 Pages) Texas Instruments – Drift, Low-Noise, Rail-to-Rail Output, 36-V, Zero-Drift Operational Amplifiers

OPA180, OPA2180, OPA4180
SBOS584D – NOVEMBER 2011 – REVISED MAY 2014
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Feature Description (continued)
8.3.2 EMI Rejection
The OPAx180 uses integrated electromagnetic interference (EMI) filtering to reduce the effects of EMI
interference from sources such as wireless communications and densely populated boards with a mix of analog
signal chain and digital components. EMI immunity can be improved with circuit design techniques; the OPAx180
benefits from these design improvements. Texas Instruments has developed the ability to accurately measure
and quantify the immunity of an operational amplifier over a broad frequency spectrum extending from 10 MHz to
6 GHz. Figure 25 shows the results of this testing on the OPAx180. Detailed information can also be found in the
application report, EMI Rejection Ratio of Operational Amplifiers (SBOA128), available for download from
www.ti.com.
160
140
120
100
80
60
40
20
0
10M
100M
1G
10G
Frequency (Hz)
Figure 25. OPAx180 EMIRR Testing
8.3.3 Phase-Reversal Protection
The OPAx180 family has an internal phase-reversal protection. Many op amps exhibit a phase reversal when the
input is driven beyond its linear common-mode range. This condition is most often encountered in noninverting
circuits when the input is driven beyond the specified common-mode voltage range, causing the output to
reverse into the opposite rail. The input of the OPAx180 prevents phase reversal with excessive common-mode
voltage. Instead, the output limits into the appropriate rail. This performance is shown in Figure 26.
18 V
Device
-18 V
37 VPP
Sine Wave
(±18.5 V)
V_I
V_O
Time (100 ms/div)
Figure 26. No Phase Reversal
14
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