Datasheet
UCC27323, UCC27324, UCC27325
UCC37323, UCC37324, UCC37325
www.ti.com
SLUS492H –JUNE 2001–REVISED MAY 2013
THERMAL INFORMATION
The useful range of a driver is greatly affected by the drive power requirements of the load and the thermal
characteristics of the IC package. In order for a power driver to be useful over a particular temperature range, the
package must allow for the efficient removal of the heat produced while keeping the junction temperature within
rated limits. The UCC37323/4/5 family of drivers is available in three different packages to cover a range of
application requirements.
As shown in the POWER DISSIPATION RATINGS table, the SOIC-8 (D) and PDIP-8 (P) packages each have a
power rating of around 0.5 W with T
A
= 70°C. This limit is imposed in conjunction with the power derating factor
also given in the table. Note that the power dissipation in our earlier example is 0.432 W with a 10-nF load, 12
VDD, switched at 300 kHz. Thus, only one load of this size can be driven using the D or P package, even if the
two onboard drivers are paralleled. The difficulties with heat removal limit the drive available in the older
packages.
The MSOP PowerPAD-8 (DGN) package significantly relieves this concern by offering an effective means of
removing the heat from the semiconductor junction. As illustrated in Reference 3 (see References), the
PowerPAD packages offer a lead-frame die pad that is exposed at the base of the package. This pad is soldered
to the copper on the PC board directly underneath the IC package, reducing the θ
JC
down to 4.7°C/W. Data is
presented in Reference 3 to show that the power dissipation can be quadrupled in the PowerPAD configuration
when compared to the standard packages. The PC board must be designed with thermal lands and thermal vias
to complete the heat removal subsystem, as summarized in Reference 4. This design allows a significant
improvement in heat sinking over that which is available in the D or P packages, and is shown to more than
double the power capability of the D and P packages.
NOTE
The PowerPAD is not directly connected to any leads of the package. However, the
PowerPad is electrically and thermally connected to the substrate which is the ground of
the device.
References
1. Power Supply Seminar SEM-1400 Topic 2, Design And Application Guide For High Speed MOSFET Gate
Drive Circuits, by Laszlo Balogh, TI Literature Number SLUP133
2. Application Note, Practical Considerations in High Performance MOSFET, IGBT and MCT Gate Drive
Circuits, by Bill Andreycak, TI Literature Number SLUA105
3. Technical Brief, PowerPad Thermally Enhanced Package, TI Literature Number SLMA002
4. Application Brief, PowerPAD Made Easy, TI Literature Number SLMA004
Copyright © 2001–2013, Texas Instruments Incorporated Submit Documentation Feedback 13
Product Folder Links: UCC27323 UCC27324 UCC27325 UCC37323 UCC37324 UCC37325