1000

100

10

1

0.1

1

10

100

| V

S | – | VO | (V)

125°C

125°C

1" Copper

85°C

25°C

25°C

1" Copper

1000

100

10

1

0.1

1

10

100

| V

S | – | VO | (V)

125°C

85°C

25°C

1000

100

10

1

0.1

1

10

100

| V

S | – | VO | (V)

125°C

85°C

25°C

OPA551, OPA552

www.ti.com

SBOS100B – JULY 1999 – REVISED JANUARY 2016

Power Dissipation (continued)

To estimate the margin of safety in a complete design (including heatsink), increase the ambient temperature

until the thermal protection is activated. Use worst-case load and signal conditions. For good reliability, the

thermal protection must trigger more than 35°C above the maximum expected ambient condition of a given

application. This limit ensures a maximum junction temperature of 125°C at the maximum expected ambient

condition.

If the OPA551 or OPA552 is to be used in an application requiring more than 0.5-W continuous power

dissipation, TI recommends that the DDPAK/TO-263 package option be used. The DDPAK/TO-263 has superior

thermal dissipation characteristics and is more easily adapted to a heatsink.

Operation from a single power supply (or unbalanced power supplies) can produce even larger power dissipation

because a larger voltage can be impressed across the conducting output transistor. Consult SBOA022 for further

information on how to calculate or measure power dissipation.

Power dissipation can be minimized by using the lowest possible supply voltage. For example, with a 200-mA

load, the output swings to within 3.5 V of the power-supply rails. Set the power supplies to no more than 3.5 V

above the maximum output voltage swing required by the application to minimize the power dissipation.

10.4 Safe Operating Area

The Safe Operating Area (SOA) curves Figure 35, Figure 36, and Figure 37 show the permissible range of

voltage and current. These curves shown represent devices soldered to a circuit board with no heatsink. The

safe output current decreases as the voltage across the output transistor (VS – VO) increases. For further insight

on SOA, consult AB-039.

Output short circuits are a very demanding case for SOA. A short-circuit to ground forces the full power-supply

voltage (V+ or V–) across the conducting transistor and produces a typical output current of 380 mA. With ±30-V

power supplies, this configuration creates an internal dissipation of 11.4 W. This dissipation far exceeds the

maximum rating and is not recommended. If operation in this region is unavoidable, use the DDPAK/TO-263

package with a heatsink.

Figure 35. PDIP-8 Safe Operating Area

Figure 36. SOIC-8 Safe Operating Area

Figure 37. DDPAK-7/TO-263 Safe Operating Area

Copyright © 1999–2016, Texas Instruments Incorporated

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