THS4032IDR Datasheet, PDF (30/47 Pages) Texas Instruments – 100-MHz LOW-NOISE HIGH-SPEED AMPLIFIERS

THS4031
THS4032
SLOS224G – JULY 1999 – REVISED MARCH 2010
www.ti.com
The actual thermal performance achieved with the THS403xDGN in its PowerPAD™ package depends on the
application. In the example above, if the size of the internal ground plane is approximately 3 inches × 3 inches
(7,62 cm × 7,62 cm), then the expected thermal coefficient, q_JA, is about 58.4°C/W. For comparison, the
non-PowerPAD™ version of the THS403x IC (SOIC) is shown. For a given q_JA, the maximum power dissipation
is shown in Figure 62 and is calculated by the following formula:
ǒ Ǔ PD +
TMAX–TA
q_JA
Where:
P_D = Maximum power dissipation of THS403x IC (watts)
T_MAX = Absolute maximum operating junction temperature (125°C)
T_A = Free-ambient air temperature (°C)
θ_JA = θ_JC + θ_CA
θ_JC = Thermal coefficient from junction to case
θ_CA = Thermal coefficient from case to ambient air (°C/W)
(3)
MAXIMUM POWER DISSIPATION
vs
AMBIENT TEMPERATURE
3
DGN Package
q_JA = 58.4 ºC/W 2 oz.
T_J = 130 ºC
2.5
Trace and Copper Pad
With Solder
SOIC Package
2 _{High-K Test PCB}
q_JA = 98 ºC/W
DGN Package
q_JA = 158.4 ºC/W 2 oz.
Trace and Copper Pad
Without Solder
1.5
1
0.5 SOIC Package
High-K Test PCB
q_JA = 166.7 ºC/W
0
-40 -20
0
20 40 60 80 100
TA- Free Air Temperature - °C
Results are with no air flow and PCB size = 3”× 3” (7,62 cm x 7,62 cm)
Figure 62. 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 (SLMA002). 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 to be considered is 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 63 to Figure 66 shows this effect, along with
the quiescent heat, with an ambient air temperature of 50°C. When using V_CC = ±5 V, heat is generally not a
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
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