OPA4188 Datasheet, PDF (19/35 Pages) Texas Instruments – Zero-Drift Operational Amplifiers

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OPA4188
SBOS641C – JUNE 2012 – REVISED NOVEMBER 2015
Feature Description (continued)
When the operational amplifier connects into a circuit, the ESD protection components are intended to remain
inactive and not become involved in the application circuit operation. However, circumstances may arise where
an applied voltage exceeds the operating voltage range of a given pin. Should this condition occur, there is a risk
that some of the internal ESD protection circuits may be biased on, and conduct current. Any such current flow
occurs through ESD cells and rarely involves the absorption device.
If there is an uncertainty about the ability of the supply to absorb this current, external Zener diodes may be
added to the supply pins. The Zener voltage must be selected such that the diode does not turn on during
normal operation. However, its Zener voltage should be low enough so that the Zener diode conducts if the
supply pin begins to rise above the safe operating supply voltage level.
8.3.4 EMI Rejection
The OPA4188 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 OPA4188
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 43 shows the results of this testing on the OPA4188. 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 43. EMIRR Testing
8.4 Device Functional Modes
The OPA4188 has a single functional mode that is operational when the power-supply voltage is greater than 4 V
(±2 V). The maximum power supply voltage for the OPA4188 is 36 V (±18 V).
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