-40 -20

0

20 40 60 80 100 120 140 160

0

0.2

0.4

0.6

0.8

1

1.2

1.4

TEMPERATURE (°C)

Operating area

Ma

xi

mu

m

the

rma

l ca

pa

bili

ty

lin

e

(SO

IC

)

Ma

ximu

m

the

rma

l ca

pab

ility

line

(MSO

P)

150°C ± 125°C

165°C/W

= 0.15W

150°C ± 125°C

235°C/W

= 0.11W

150°C ± 25°C

165°C/W

= 0.76W

150°C ± 25°C

235°C/W

= 0.53W

LM7321, LM7322

SNOSAW8D – MAY 2008 – REVISED MARCH 2013

www.ti.com

±12V supplies, a 600

Ω load, and triangular waveform power dissipation in the output stage is calculated as:

(1)

The maximum power dissipation allowed at a certain temperature is a function of maximum die junction

(2)

For the LM7321/LM7321Q/LM7322/LM7322Q, the maximum junction temperature allowed is 150°C at which no

power dissipation is allowed. The power capability at 25°C is given by the following calculations:

For VSSOP package:

(3)

For SOIC package:

(4)

Similarly, the power capability at 125°C is given by:

For VSSOP package:

(5)

For SOIC package:

(6)

Figure 74 shows the power capability vs. temperature for VSSOP and SOIC packages. The area under the

maximum thermal capability line is the operating area for the device. When the device works in the operating

intersection of ambient temperature and package power is above the maximum thermal capability line, the

junction temperature will exceed 150°C and this should be strictly prohibited.

Figure 74. Power Capability vs. Temperature

When high power is required and ambient temperature can't be reduced, providing air flow is an effective

approach to reduce thermal resistance therefore to improve power capability.

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