Power Supply

ESD Cell

IN±

IN+

+

±

TVS

TVS

TLVx197-Q1

+

±

100

100

24

TLV197-Q1, TLV2197-Q1, TLV4197-Q1

SBOS935 – APRIL 2020

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Product Folder Links: TLV197-Q1 TLV2197-Q1 TLV4197-Q1

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7.3.7 Electrical Overstress

Designers often ask questions about the capability of an operational amplifier to withstand electrical overstress

(EOS). These questions tend to focus on the device inputs, but may involve the supply voltage pins or even the

output pin. Each of these different pin functions have electrical stress limits determined by the voltage breakdown

characteristics of the particular semiconductor fabrication process and specific circuits connected to the pin.

Additionally, internal electrostatic discharge (ESD) protection is built into these circuits to protect them from

accidental ESD events both before and during product assembly.

Having a good understanding of this basic ESD circuitry and its relevance to an electrical overstress event is

helpful. Figure 40 shows an illustration of the ESD circuits contained in the TLVx197-Q1 (indicated by the dashed

line area). The ESD protection circuitry involves several current-steering diodes connected from the input and

output pins and routed back to the internal power-supply lines, where the diodes meet at an absorption device or

the power-supply ESD cell, internal to the operational amplifier. This protection circuitry is intended to remain

inactive during normal circuit operation.

Figure 40. 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.