TLV247xQ1, TLV247xAQ1

FAMILY OF 600 µA/Ch 2.8MHz RAILTORAIL INPUT/OUTPUT

HIGHDRIVE OPERATIONAL AMPLIFIERS

SGLS180B − AUGUST 2003 − REVISED APRIL 2008

18

POST OFFICE BOX 655303

APPLICATION INFORMATION

general PowerPAD design considerations (continued)

TJ = 150°C

4

3

2

0

−55 −40

−10

20 35

5

6

MAXIMUM POWER DISSIPATION

vs

FREE-AIR TEMPERATURE

7

65

95

125

1

TA − Free-Air Temperature − °C

DGN Package

Low-K Test PCB

θJA = 52.3°C/W

SOT-23 Package

Low-K Test PCB

θJA = 324°C/W

−25

5

50

80

110

PWP Package

Low-K Test PCB

θJA = 29.7°C/W

SOIC Package

Low-K Test PCB

θJA = 176°C/W

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

Figure 40.

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. Figure 41 to Figure 46 show this effect,

along with the quiescent heat, with an ambient air temperature of 70

is generally not a heat problem with an ambient air temperature of 70

packages are severely limited in the amount of heat it can dissipate. The other key factor when looking at these

graphs 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,

capability increases. The currents and voltages shown in these 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.