OPA378_1 Datasheet, PDF (11/24 Pages) Texas Instruments – Low-Noise, 900kHz, RRIO, Precision OPERATIONAL AMPLIFIER Zerø-Drift Series

OPA378
OPA2378
www.ti.com ..................................................................................................................................................... SBOS417C – JANUARY 2008 – REVISED JUNE 2009
ELECTRICAL OVERSTRESS
Designers often ask questions about the capability of
an operational amplifier to withstand electrical
overstress. 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.
It is helpful to have a good understanding of this
basic ESD circuitry and its relevance to an electrical
overstress event. Figure 29 shows the ESD circuits
contained in the OPA378 (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 they meet at an absorption
device internal to the operational amplifier. This
protection circuitry is intended to remain inactive
during normal circuit operation.
R_F
ESD
V-
ESD
+V_S
+V
OPA378
R_I
-In
+In
I_D
V_IN(1)
Op-Amp
Core
ESD
ESD
V+
-V
ESD Current-
Steering Diodes
Out
Edge-Triggered ESD
Absorption Circuit
R_L
-V_S
(1) V_IN = +V_S + 500mV.
Figure 29. Equivalent Internal ESD Circuitry and Its Relation to a Typical Circuit Application
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