TLV9152 datasheet(19/45 Pages) TI

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7.3.2 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 TLV915x-Q1 is 150°C.

Exceeding this temperature causes damage to the device. The TLV915x-Q1 has a thermal protection feature

that reduces 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 170°C. Figure 7-2 shows an application example for

the TLV9151-Q1 that has significant self heating because of its power dissipation (0.81 W). Thermal calculations

indicate that for an ambient temperature of 65°C, the device junction temperature will reach 177°C. The actual

device, however, turns off the output drive to recover towards a safe junction temperature. Figure 7-2 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 the internal limit, the thermal

protection forces the output to a high-impedance state and the output is pulled to ground through resistor RL.

If the condition that caused excessive power dissipation is not removed, the amplifier will oscillate between a

shutdown and enabled state until the output fault is corrected.

140ºC

3 V

0 V

150°C

16 V

100

VIN

3 V

–

OUT = 30 mA

TLV9151

TA = 100°C

PD = 0.39W

JA = 138.7°C/W

TJ = 138.7°C/W × 0.39W + 100°C

TJ = 154.1°C (expected)

–

Normal

Operation

Output

High-Z

Figure 7-2. Thermal Protection

7.3.3 Capacitive Load and Stability

The TLV915x-Q1 features a resistive output stage capable of driving moderate capacitive loads, and by

leveraging an isolation resistor, the device can easily be configured to drive large capacitive loads. Increasing

the gain enhances the ability of the amplifier to drive greater capacitive loads; see Figure 7-3 and Figure 7-4.

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.

Cap Load (pF)

120

160

200

240

280

320

360

C008

RISO = 0 :, Positive Overshoot

RISO = 0 :, Negative Overshoot

RISO = 50 :, Positive Overshoot

RISO = 50 :, Negative Overshoot

Figure 7-3. Small-Signal Overshoot vs Capacitive

Load (10-mV Output Step, G = 1)

Cap Load (pF)

120

160

200

240

280

320

360

C007

RISO = 0 :, Positive Overshoot

RISO = 0 :, Negative Overshoot

RISO = 50 :, Positive Overshoot

RISO = 50 :, Negative Overshoot

Figure 7-4. Small-Signal Overshoot vs Capacitive

Load (10-mV Output Step, G = –1)

For additional drive capability in unity-gain configurations, improve capacitive load drive by inserting a small

resistor, RISO, in series with the output, as shown in Figure 7-5. This resistor significantly reduces ringing

and maintains DC performance for purely capacitive loads. However, if a resistive load is in parallel with the

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TLV9152-Q1, TLV9154-Q1

SBOSA23B – MAY 2020 – REVISED MARCH 2021

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