THS6072

LOW-POWER ADSL DIFFERENTIAL RECEIVER

SLOS290B – FEBRUARY 2000 – REVISED JUNE 2001

20

POST OFFICE BOX 655303

APPLICATION INFORMATION

general PowerPAD design considerations (continued)

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 multiamplifier 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 48 and Figure 49 show this

effect, along with the quiescent heat, with an ambient air temperature of 50

°C. Obviously, as the ambient

temperature increases, the limit lines shown will drop accordingly. The area under each respective limit line is

considered the safe operating area. Any condition above this line will exceed the amplifier’s limits and failure

using

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,

and the heat dissipation capability increases. The currents and voltages shown in these graphs are for the total

package.

Figure 48

Package With

θJA ≤ 64°C/W

SO-8 Package

θJA = 98°C/W

High-K Test PCB

VCC = ± 5 V

TJ = 150°C

TA = 50°C

Both Channels

100

80

40

0

01

2

3

140

180

200

45

160

120

60

20

| VO | – RMS Output Voltage – V

Maximum Output

Current Limit Line

THS6072

MAXIMUM RMS OUTPUT CURRENT

vs

RMS OUTPUT VOLTAGE DUE TO THERMAL LIMITS

SO-8 Package

θJA = 167°C/W

Low-K Test PCB

Safe Operating Area

Figure 49

100

10

03

6

9

1000

12

15

Maximum Output

Current Limit Line

| VO | – RMS Output Voltage – V

VCC = ± 15 V

TJ = 150°C

TA = 50°C

Both Channels

THS6072

MAXIMUM RMS OUTPUT CURRENT

vs

RMS OUTPUT VOLTAGE DUE TO THERMAL LIMITS

1

SO-8 Package

θJA = 167°C/W

Low-K Test PCB

DGN Package

θJA = 58.4°C/W

Safe Operating Area

SO-8 Package

θJA = 98°C/W

High-K Test PCB