Datasheet

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THERMAL ANALYSIS
DESIGN TOOLS
Evaluation Fixtures and Application Support
P
Dmax
+
T
max
–T
A
q
JA
where:
P
Dmax
is the maximum power dissipation in the amplifier (W).
T
max
is the absolute maximum junction temperature (°C).
T
A
is the ambient temperature (°C).
θ
JA
= θ
JC
+ θ
CA
θ
JC
is the thermal coefficient from the silicon junctions to
the case (°C/W).
θ
CA
is the thermal coefficient from the case to ambient air
(°C/W).
4
3
2
0
-40 -20 0 20
- Maximum Power Dissipation - W
5
6
7
40 60 80
T
A
- Ambient Temperature - °C
P
D
16-Pin RGT Package
θ
JA
= 39.5°C/W for 16-Pin MSOP (RGT)
T
J
= 150°C, No Airflow
1
THS4302
SLOS403H – OCTOBER 2002 – REVISED AUGUST 2006
When determining whether or not the device satisfies
the maximum power dissipation requirement, it is
The THS4302 device does not incorporate automatic
important to consider not only quiescent power
thermal shutoff protection, so the designer must take
dissipation, but also dynamic power dissipation. Often
care to ensure that the design does not violate the
maximum power is difficult to quantify because the
absolute maximum junction temperature of the
signal pattern is inconsistent, but an estimate of the
device. Failure may result if the absolute maximum
RMS power dissipation can provide visibility into a
junction temperature of 150 ° C is exceeded.
possible problem.
The thermal characteristics of the device are dictated
by the package and the PC board. For a given Θ
JA
,
maximum power dissipation for a package can be
calculated using the following formula.
Information
Texas Instruments is committed to providing its
customers with the highest quality of applications
support. To support this goal, an evaluation board
has been developed for the THS4302 operational
amplifier. The evaluation board is available and easy
to use allowing for straight-forward evaluation of the
device. This evaluation board can be obtained by
ordering through the Texas Instruments Web site,
www.ti.com, or through your local Texas Instruments
Sales Representative. A schematic for the evaluation
(1)
board with default component values is shown in
The THS4302 is offered in a 16-pin leadless MSOP
Figure 52 . Unpopulated footprints are shown to
with PowerPAD. The thermal coefficient for the
provide insight into design flexibility
MSOP PowerPAD package is substantially improved
Computer simulation of circuit performance using
over the traditional packages. Maximum power
SPICE is often useful when analyzing the
dissipation levels are depicted in the graph below.
performance of analog circuits and systems. This is
The data for the RGT package assumes a board
particularly true for video and RF amplifier circuits
layout that follows the PowerPAD layout guidelines
where parasitic capacitance and inductance can have
referenced above and detailed in the PowerPAD
a major effect on circuit performance. A SPICE model
application notes in the Additional Reference Material
for the THS4500 family of devices is available
section at the end of the data sheet.
through the Texas Instruments web site (www.ti.com ).
The Product Information Center (PIC) is available for
design assistance and detailed product information.
These models do a good job of predicting small
signal ac and transient performance under a wide
variety of operating conditions. They are not intended
to model the distortion characteristics of the amplifier,
nor do they attempt to distinguish between the
package types in their small signal ac performance.
Detailed information about what is and is not modeled
is contained in the model file itself.
Figure 51. Maximum Power Dissipation vs
Ambient Temperature
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Product Folder Link(s): THS4302