THS6062 Datasheet, PDF (27/31 Pages) Texas Instruments – LOW-NOISE ADSL DUAL DIFFERENTIAL RECEIVER

THS6062
LOW-NOISE ADSL DUAL DIFFERENTIAL RECEIVER
SLOS228B – JANUARY 1999 – REVISED JUNE 1999
APPLICATION INFORMATION
general PowerPAD design considerations (continued)
MAXIMUM POWER DISSIPATION
vs
FREE-AIR TEMPERATURE
3.5
DGN Package
θ_JA = 58.4°C/W
TJ = 150°C
3
2 oz. Trace And Copper Pad
With Solder
2.5
SOIC Package
High-K Test PCB
2 ^θJA ^{= 98°C/W}
DGN Package
θ_JA = 158°C/W
2 oz. Trace And
Copper Pad
Without Solder
1.5
1
0.5 ^{SOIC Package}
Low-K Test PCB
θ_JA = 167°C/W
0
–40 –20 0 20 40 60 80 100
TA – Free-Air Temperature – °C
NOTE A: Results are with no air flow and PCB size = 3”× 3”
Figure 48. Maximum Power Dissipation vs Free-Air Temperature
More complete details of the PowerPAD installation process and thermal management techniques can be found
in the Texas Instruments Technical Brief, PowerPAD Thermally Enhanced Package. This document can be
found at the TI web site (www.ti.com) by searching on the key word PowerPAD. The document can also be
ordered through your local TI sales office. Refer to literature number SLMA002 when ordering.
The next thing that should be considered 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 a multiamplifier device. 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 49 and Figure 50
show this effect, along with the quiescent heat, with an ambient air temperature of 50°C. When using
V_CC = 5 V or ±5 V, there is generally not a heat problem, even with SOIC packages. But, when using
V_CC = ±15 V, the SOIC package is 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, θ_JA decreases
and the heat dissipation capability increases. The currents and voltages shown in these graphs are for the total
package. Because the THS6062 is a dual amplifier, the sum of the RMS output currents and voltages should
be used to choose the proper package.
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