ꢀꢁꢁ ꢂ ꢃꢄ ꢂ ꢅ ꢆ ꢀꢁ ꢁꢂ ꢃꢄ ꢂꢂ
ꢀꢁꢁ ꢄ ꢃꢄ ꢂ ꢅ ꢆ ꢀꢁ ꢁꢄ ꢃꢄ ꢂꢂ
SLUS504C − SEPTEMBER 2002 − REVISED NOVEMBER 2004
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 = 70°C. This limit is imposed in conjunction with the power derating factor also
A
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 could be driven using the D or P packag. 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 the D or P packages, and is shown to more than double the power capability
of the D and P packages.
Note that the PowerPADt 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 Performance MOSFET, IGBT and MCT Gate Drive 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
Dual 4-A Low-Side Drivers
PACKAGES
MSOP−8 PowerPAD, SOIC−8, PDIP−8
MSOP−8 PowerPAD, SOIC−8, PDIP−8
TSSOP−8, SOIC−8, PDIP−8
TSSOP−8, SOIC−8, PDIP−8
5-Pin SOT−23
UCC37323/4/5
UCC27423/4/5
TPS2811/12/13
TPS2814/15
Dual 4-A Low-Side Drivers with Enable
Dual 2-A Low-Side Drivers with Internal Regulator
Dual 2-A Low-Side Drivers with Two Inputs per Channel
Single 2-A Low-Side Driver with Internal Regulator
Single 2-A Low-Side Driver
TPS2816/17/18/19
TPS2828/29
5-Pin SOT−23
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