THS3110_14 Datasheet, PDF (23/38 Pages) Texas Instruments – LOW-NOISE, HIGH-VOLTAGE, CURRENT-FEEDBACK OPERATIONAL AMPLIFIERS

THS3110
THS3111
www.ti.com........................................................................................................................................ SLOS422E – SEPTEMBER 2003 – REVISED OCTOBER 2009
entire circumference of the plated-through hole.
6. The top-side solder mask should leave the
terminals of the package and the thermal pad
area with its five holes exposed. The bottom-side
solder mask should cover the five holes of the
thermal pad area. This prevents solder from
being pulled away from the thermal pad area
during the reflow process.
7. Apply solder paste to the exposed thermal pad
area and all of the IC terminals.
8. With these preparatory steps in place, the IC is
simply placed in position and run through the
solder reflow operation as any standard
surface-mount component. This results in a part
that is properly installed.
Maximum power dissipation levels are depicted in
Figure 65 for the available packages. The data for the
PowerPAD packages assume a board layout that
follows the PowerPAD layout guidelines referenced
above and detailed in the PowerPAD application note
(literature number SLMA002). Figure 65 also
illustrates the effect of not soldering the PowerPAD to
a PCB. The thermal impedance increases
substantially which may cause serious heat and
performance issues. Be sure to always solder the
PowerPAD to the PCB for optimum performance.
T_J = 125°C
POWER DISSIPATION AND THERMAL
CONSIDERATIONS
The THS3110 and THS3111 incorporate automatic
thermal shutoff protection. This protection circuitry
shuts down the amplifier if the junction temperature
exceeds approximately +160°C. When the junction
temperature reduces to approximately +140°C, the
amplifier turns on again. But, for maximum
performance and reliability, the designer must take
care to ensure that the design does not exceed a
junction temperature of +125°C. Between +125°C
and +150°C, damage does not occur, but the
performance of the amplifier begins to degrade and
long term reliability suffers. The thermal
characteristics of the device are dictated by the
package and the PC board. Maximum power
dissipation for a given package can be calculated
using the following formula.
P
= ^{TMax - TA}
DMax
q_JA
(1)
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)
For systems where heat dissipation is more critical,
the THS3110 and THS3111 are offered in an
MSOP-8 with PowerPAD package offering even
better thermal performance. The thermal coefficient
for the PowerPAD packages are substantially
improved over the traditional SOIC.
T_A - Free-Air Temperature - °C
Results are with no airflow and PCB size = 3 in × 3 in (7,62 mm ×
7,62 mm); θ_JA = 58.4°C/W for MSOP-8 with PowerPAD (DGN); θ_JA
= 95°C/W for SOIC-8 High-K Test PCB (D); θ_JA = 158°C/W for
MSOP-8 with PowerPAD, without solder.
Figure 65. Maximum Power Distribution
vs Ambient Temperature
When determining whether or not the device satisfies
the maximum power dissipation requirement, it is
important to not only consider quiescent power
dissipation, but also dynamic power dissipation. Often
times, this is difficult to quantify because the signal
pattern is inconsistent, but an estimate of the RMS
power dissipation can provide visibility into a possible
problem.
DESIGN TOOLS
Evaluation Fixtures, Spice Models, and
Application Support
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 THS3110 and THS3111
operational amplifiers. The board is easy to use,
allowing for straightforward evaluation of the device.
The evaluation board can be ordered through the
Texas Instruments web site, www.ti.com, or through
your local Texas Instruments sales representative.
Copyright © 2003–2009, Texas Instruments Incorporated
Product Folder Link(s): THS3110 THS3111
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