OPA2197IDRG4 datasheet(22/56 Pages) TI2

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VOUT

140ºC

3 V

0 V

Normal

Operation

Output

High-Z

150°C

+30 V

100

VIN

3 V

IOUT = 30 mA

OPAx197

TA = 65°C

PD = 0.81W

JA = 116°C/W

TJ = 116°C/W × 0.81W + 65°C

TJ = 159°C (expected)

Time (200 Ps/div)

Output

Input

OPA197, OPA2197, OPA4197

SBOS737C – JANUARY 2016 – REVISED MARCH 2018

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Product Folder Links: OPA197 OPA2197 OPA4197

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7.3.3 Phase Reversal Protection

The OPAx197 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 OPAx197 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 45.

Figure 45. No Phase Reversal

7.3.4 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 OPAx197 is 150°C.

Exceeding this temperature causes damage to the device. The OPAx197 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 46 shows an application example for

the OPA197 that has significant self heating (159°C) because of its 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 46 depicts

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.

Figure 46. Thermal Protection

7.3.5 Capacitive Load and Stability

The OPAx197 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 47 and Figure 48. The particular op amp circuit

configuration, layout, gain, and output loading are some of the factors to consider when establishing whether an

amplifier will be stable in operation.

OPA2197IDRG4 Datasheet(PDF) 22 Page - Texas Instruments

OPA2197IDRG4 Datasheet(HTML) 22 Page - Texas Instruments

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