8.3 Feature Description

8.3.1 Input Overvoltage Protection

The inputs of the OPAx206 are individually protected for voltages up to ±40 V beyond either supply. For

example, a common-mode voltage anywhere between –55 V and +55 V does not cause damage when powered

from ±15-V supplies. Internal circuitry on each input provides low series impedance under normal signal

conditions thus maintaining high performance under normal operating conditions. If the input is overloaded,

the protection circuitry limits the input current to a value of approximately 4.8 mA.

During an input overvoltage condition, current flows through the input protection diodes into the power supplies,

as shown in Figure 8-1. If the power supplies are unable to sink current, then Zener diode clamps (ZD1 and

ZD2) must be placed on the power supplies to provide a current pathway to ground. Figure 8-2 shows that

during an overvoltage condition, the input bias current of the inputs increase.

+VS

-VS

Overvoltage

Protection

IN

Input Transistor

+V

-V

+

±

Input Voltage

Source

ZD1

ZD2

Figure 8-1. OPAx206 Input Overvoltage Current Path

Figure 8-2 shows the input current for input voltages from –55 V to +55 V when the OPAx206 are powered by

±15-V supplies.

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OPA206, OPA2206

SBOSA11D – MARCH 2020 – REVISED MARCH 2023

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