P

D +

T

MAX

–T

A

q

JA

Where:

= Maximum power dissipation of TLV411x IC (watts)

= Free-ambient air temperature (

°C)

(2)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

−55 −40 −25 −10 5

20 35 50 65 80 95 110 125

G026

DGN Package

Low-K Test PCB

SOIC Package

Low-K Test PCB

TLV4110-EP, TLV4111-EP

TLV4112-EP, TLV4113-EP

For a given

θ

NOTE: Results are with no air flow and using JEDEC Standard Low-K test PCB.

Figure 32. Maximum Power Dissipation vs Free-Air Temperature

The next consideration is the package constraints. The two sources of heat within an amplifier are quiescent

power and output power. The designer should never forget about the quiescent heat generated within the device,

especially multi-amplifier devices. Because these devices have linear output stages (Class A-B), most of the heat

dissipation is at low output voltages with high output currents.

The other key factor when dealing with power dissipation is how the devices are mounted on the PCB. The

PowerPAD devices are extremely useful for heat dissipation. But, the device should always be soldered to a

copper plane to fully use the heat dissipation properties of the PowerPAD. The SOIC package, on the other

hand, is highly dependent on how it is mounted on the PCB. As more trace and copper area is placed around the

device,

θ

graphs are for the total package. For the dual or quad amplifier packages, the sum of the RMS output currents

and voltages should be used to choose the proper package.

16

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