Power-Supply

ESD Cell

100

100

VSS

VDD

IN–

IN+

+

–

R1

RS

RF

TVS

TVS

RL

VIN

+VS

–VS

ID

+

–

Figure 7-10. Equivalent Internal ESD Circuitry Relative to a Typical Circuit Application

An ESD event is very short in duration and very high voltage (for example; 1 kV, 100 ns), whereas an EOS event

is long duration and lower voltage (for example; 50 V, 100 ms). The ESD diodes are designed for out-of-circuit

ESD protection (that is, during assembly, test, and storage of the device before being soldered to the PCB).

During an ESD event, the ESD signal is passed through the ESD steering diodes to an absorption circuit

(labeled ESD power-supply circuit). The ESD absorption circuit clamps the supplies to a safe level.

Although this behavior is necessary for out-of-circuit protection, excessive current and damage is caused if

activated in-circuit. A transient voltage suppressors (TVS) can be used to prevent against damage caused by

turning on the ESD absorption circuit during an in-circuit ESD event. Using the appropriate current limiting

resistors and TVS diodes allows for the use of device ESD diodes to protect against EOS events.

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OPA4991-EP

SBOSAC6B – JUNE 2022 – REVISED NOVEMBER 2022

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