OPA192-Q1 Datasheet, PDF (26/42 Pages) Texas Instruments – 36-V, Precision, Rail-to-Rail Input/Output, Low-Offset Voltage, Low-Input Bias Current Op Amp With e-trim

OPA192-Q1, OPA2192-Q1, OPA4192-Q1
SBOS850 – MAY 2017
www.ti.com
8.3.3 Phase Reversal Protection
The OPAx192-Q1 family has internal phase-reversal protection. Many op amps exhibit a phase reversal when
the input is driven beyond its 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 OPAx192-Q1 is a rail-to-rail input op amp; 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 58.
+ 18 V
-
OPA192-Q1
+
+
- ^{37 VPP -18 V}
Sine Wave
(±18.5V)
VOUT
V_IN
V_OUT
Time (200 μs/div)
Figure 58. No Phase Reversal
8.3.4 Thermal Protection
The internal power dissipation of any amplifier causes its internal (junction) temperature to rise. This
phenomenon is called self heating. The absolute maximum junction temperature of the OPAx192-Q1 is 150°C.
Exceeding this temperature causes damage to the device. The OPAx192-Q1 has a thermal protection feature
that prevents damage from self heating. The protection works by monitoring the temperature of the device and
turning off the op amp output drive for temperatures above 140°C. Figure 59 shows an application example for
the OPAx192-Q1 that has significant self heating (159°C) because of the power dissipation (0.81 W). Thermal
calculations indicate that for an ambient temperature of 65°C the device junction temperature must reach 187°C.
The actual device, however, turns off the output drive to maintain a safe junction temperature. Figure 59 shows
how the circuit behaves during thermal protection. During normal operation, the device acts as a buffer so the
output is 3 V. When self heating causes the device junction temperature to increase above 140°C, the thermal
protection forces the output to a high-impedance state and the output is pulled to ground through resistor RL.
+30 V
3V
TA = 65°C
PD = 0.81W
JA = 116°C/W
0V
TJ = 116°C/W × 0.81W + 65°C
TJ = 159°C (expected)
OPAx192-Q1
+ V_IN
± 3V
IOUT = 30 mA
+
RL _{3 V}
100 Ÿ _±
Normal
Operation
Output
High-Z
150°C
140ºC
Copyright © 2017, Texas Instruments Incorporated
Figure 59. Thermal Protection
8.3.5 Capacitive Load and Stability
The OPAx192-Q1 features a patented output stage capable of driving large capacitive loads, and in a unity-gain
configuration, directly drives up to 1 nF of pure capacitive load. Increasing the gain enhances the ability of the
amplifier to drive greater capacitive loads; see Figure 60 and Figure 61. The particular op amp circuit
configuration, layout, gain, and output loading are some of the factors to consider when establishing whether an
amplifier is stable in operation.
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