DRV8312_14 Datasheet, PDF (24/36 Pages) Texas Instruments – Three Phase PWM Motor Driver

DRV8312
DRV8332
SLES256D – MAY 2010 – REVISED JANUARY 2014
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THERMAL INFORMATION
The thermally enhanced package provided with the DRV8332 is designed to interface directly to heat sink using
a thermal interface compound in between, (e.g., Ceramique from Arctic Silver, TIMTronics 413, etc.). The heat
sink then absorbs heat from the ICs and couples it to the local air. It is also a good practice to connect the
heatsink to system ground on the PCB board to reduce the ground noise.
R_θJA is a system thermal resistance from junction to ambient air. As such, it is a system parameter with the
following components:
• R_θJC (the thermal resistance from junction to case, or in this example the power pad or heat slug)
• Thermal grease thermal resistance
• Heat sink thermal resistance
The thermal grease thermal resistance can be calculated from the exposed power pad or heat slug area and the
thermal grease manufacturer's area thermal resistance (expressed in °C-in ²/W or °C-mm²/W). The approximate
exposed heat slug size is as follows:
• DRV8332, 36-pin PSOP3 …… 0.124 in² (80 mm ²)
The thermal resistance of a thermal pad is considered higher than a thin thermal grease layer and is not
recommended. Thermal tape has an even higher thermal resistance and should not be used at all. Heat sink
thermal resistance is predicted by the heat sink vendor, modeled using a continuous flow dynamics (CFD) model,
or measured.
Thus the system R_θJA = R_θJC + thermal grease resistance + heat sink resistance.
See the TI application report, IC Package Thermal Metrics (SPRA953A), for more thermal information.
DRV8312 Thermal Via Design Recommendation
Thermal pad of the DRV8312 is attached at bottom of device to improve the thermal capability of the device. The
thermal pad has to be soldered with a very good coverage on PCB in order to deliver the power specified in the
datasheet. The figure below shows the recommended thermal via and land pattern design for the DRV8312. For
additional information, see TI application report, PowerPad Made Easy (SLMA004B) and PowerPad Layout
Guidelines (SOLA120).
Figure 16. DRV8312 Thermal Via Footprint
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