SLUU130A – September 2002 – Revised February 2003
5 PowerPAD Packaging
The TPS4000X family is available in the DGQ version of TI’s PowerPAD thermally enhanced package. In the PowerPAD , a thermally conductive epoxy is utilized to attach the integrated circuit die to the leadframe die pad, which is exposed on the bottom of the completed package. The leadframe die pad can be soldered to the PCB using standard solder flow techniques when maximum heat dissipation is required. However, depending on power dissipation requirements, the PowerPAD may not need to soldered to the PCB.
The PowerPAD package helps to keep the junction temperature rise relatively low even with the power dissipation inherent in the onboard MOSFET drivers. This power loss is proportional to switching frequency, drive voltage, and the gate charge needed to enhance the
To effectively remove heat from the PowerPAD package, a thermal land should be provided directly underneath the package whether the package needs to be soldered or not. This thermal land usually has vias that help to spread heat to internal copper layers and/or the opposite side of the PCB. The vias should not have thermal reliefs that are often used on ground planes, because this reduces the copper area which transfers heat. Additionally, the vias should be small enough so that the holes are effectively plugged when plated. This prevents the solder from wicking away from the connection between the PCB surface and the bottom of the part. A typical construction utilizes a few vias of 0.013” diameter plated with 1 ounce copper in the land under the TPS40003. A typical layout pattern is shown in Figure 2, but does not show the copper land which would encompass the vias above and below the device.
2.92mm
(0.115”)
0.5mm
(0.0197”)
Minimum
PowerPad ”Y” 1.7mm (0.068”)
0.28mm | 1.40mm | Via Dia. |
(0.055”) | ||
(0.011”) |
| 0.33mm |
|
| (0.013”) |
Miminum
PowerPad ”X” 
1.3mm
(0.050”)
Figure 3. PowerPAD PCB Layout Guidelines
The Texas Instrument document, PowerPAD Thermally Enhanced Package Application Report (SLMA002) should be consulted for more information on the PowerPAD package. This report offers
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