R

F

Op-Amp

Core

R

I

R

L

V

(1)

IN

I

D

-In

Out

+In

ESDCurrent-

SteeringDiodes

Edge-TriggeredESD

AbsorptionCircuit

+V

S

+V

-V

-V

S

OPA378

ESD

ESD

ESD

ESD

V+

V-

OPA378

OPA2378

SBOS417D – JANUARY 2008 – REVISED OCTOBER 2009

www.ti.com

ELECTRICAL OVERSTRESS

It is helpful to have a good understanding of this

basic ESD circuitry and its relevance to an electrical

Designers often ask questions about the capability of

overstress event. Figure 30 shows the ESD circuits

an

operational

amplifier

to

withstand

electrical

contained in the OPA378 (indicated by the dashed

overstress. These questions tend to focus on the

line area). The ESD protection circuitry involves

device inputs, but may involve the supply voltage pins

several current-steering diodes connected from the

or even the output pin. Each of these different pin

input and output pins and routed back to the internal

functions have electrical stress limits determined by

power-supply lines, where they meet at an absorption

the

voltage

breakdown

characteristics

of

the

device internal to the operational amplifier. This

particular semiconductor fabrication process and

protection circuitry is intended to remain inactive

specific circuits connected to the pin. Additionally,

during normal circuit operation.

internal electrostatic discharge (ESD) protection is

built

into

these

circuits

to

protect

them

from

accidental ESD events both before and during

product assembly.

(1) VIN = +VS + 500mV.

Figure 30. Equivalent Internal ESD Circuitry and Its Relation to a Typical Circuit Application

12

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