OPA191 Datasheet, PDF (28/45 Pages) Texas Instruments – Low Offset Voltage, Low Input Bias Current Op Amp

OPA191, OPA2191, OPA4191
SBOS701 – DECEMEBER 2015
www.ti.com
8.3.7 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. See Figure 59 for an illustration of the ESD circuits contained in the OPAx191 (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.
TVS
RF
R1
IN±
RS
IN+
ID
+
VIN
±
100 Ÿ
100 Ÿ
+VS
VDD
OPAx191
±
+
VSS
Power-Supply
RL
ESD Cell
±VS
TVS
Figure 59. Equivalent Internal ESD Circuitry Relative to a Typical Circuit Application
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