OPA191_017 Datasheet, PDF (25/51 Pages) Texas Instruments – 36-V, Low Power, Precision, CMOS, Rail-to-Rail Input/Output, Low Offset Voltage, Low Input Bias Current Op Amp

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OPA191, OPA2191, OPA4191
SBOS701A – DECEMEBER 2015 – REVISED APRIL 2016
8.3.3 Phase Reversal Protection
The OPAx191 family has internal phase-reversal protection. Many op amps exhibit phase reversal when the
input is driven beyond the linear common-mode range. This condition is most often encountered in noninverting
circuits when the input is driven beyond the specified common-mode voltage range, causing the output to
reverse into the opposite rail. The OPAx191 is a rail-to-rail input op amp, and therefore the common-mode range
can extend up to the rails. Input signals beyond the rails do not cause phase reversal; instead, the output limits
into the appropriate rail. This performance is shown in Figure 54.
V_IN
V_OUT
Time (35 ms/div)
C017
Figure 54. No Phase Reversal
8.3.4 Thermal Protection
The internal power dissipation of any amplifier causes the internal (junction) temperature to rise. This
phenomenon is called self heating. The OPAx191 has a thermal protection feature that prevents damage from
self heating.
This thermal protection works by monitoring the temperature of the output stage and turning off the op amp
output drive for temperatures above approximately 180°C. Thermal protection forces the output to a high-
impedance state. The OPAx191 is also designed with approximately 30°C of thermal hysteresis. Thermal
hysteresis prevents the output stage from cycling in and out of the high-impedance state. The OPAx191 returns
to normal operation when the output stage temperature falls below approximately 150°C.
The absolute maximum junction temperature of the OPAx191 is 150°C. Exceeding the limits shown in the
Absolute Maximum Ratings table may cause damage to the device. Thermal protection triggers at 180°C
because of unit-to-unit variance, but does not interfere with device operation up to the absolute maximum ratings.
This thermal protection is not designed to prevent this device from exceeding absolute maximum ratings, but
rather from excessive thermal overload.
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