Datasheet

UCC27321 , UCC27322
UCC37321, UCC37322
www.ti.com
SLUS504G SEPTEMBER 2002REVISED 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 device 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 UCC37321/2 family of drivers is available in three different packages to cover a range of
application requirements.
As shown in the power dissipation rating 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 0.432W with a 10-nF load, 12 VDD,
switched at 300 kHz. Thus, only one load of this size could be driven using the D or P package. The difficulties
with heat removal limit the drive available in the D or P 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, the PowerPAD packages offer
a leadframe 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 device package, reducing the θjc 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 allows a significant improvement in heatsinking over
that available in theDor P packages, and is shown to more than double the power capability of the D and P
packages.
Note that the PowerPAD™ is not directly connected to any leads of the package. However, it is electrically and
thermally connected to the substrate which is the ground of the device.
References.
1. SEM-1400, Topic 2, A Design and Application Guide for High Speed Power MOSFET Gate Drive Circuits, TI
Literature No. SLUP133
2. U-137, Practical Considerations in High PerformanceMOSFET, IGBT andMCTGateDrive Circuits, by Bill
Andreycak, TI Literature No. SLUA105
3. Technical Brief, PowerPad Thermally Enhanced Package, TI Literature No. SLMA002
4. Application Brief, PowerPAD Made Easy, TI Literature No. SLMA004
Related Products
PRODUCT DESCRIPTION PACKAGES
UCC37323/4/5 Dual 4-A Low-Side Drivers MSOP–8 PowerPAD, SOIC–8, PDIP–8
UCC27423/4/5 Dual 4-A Low-Side Drivers with Enable MSOP–8 PowerPAD, SOIC–8, PDIP–8
TPS2811/12/13 Dual 2-A Low-Side Drivers with Internal Regulator TSSOP–8, SOIC–8, PDIP–8
TPS2814/15 Dual 2-A Low-Side Drivers with Two Inputs per Channel TSSOP–8, SOIC–8, PDIP–8
TPS2816/17/18/19 Single 2-A Low-Side Driver with Internal Regulator 5-Pin SOT–23
TPS2828/29 Single 2-A Low-Side Driver 5-Pin SOT–23
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