DRV8332 thermal details

Wayne Fite

Intellectual 1945 points

Other Parts Discussed in Thread: DRV8332

The Rjc for the DRV8332 (DKD package) is given in the data sheet as 0.9C/W. Is this the thermal resistance from each mosfet junction to the exposed surface of the heat slug or is this the combined thermal resistance of all six mosfets in parallel to the exposed surface of the heat slug.?

Also is the heat slug of the DRV8332 isolated from the mosfets or is an electrical insulator needed between the DRV8332 heat slug and an external aluminum heatsink?

The reason for my questions is that I am trying to develop a thermal resistance model from each mosfet junction to external ambient in order to calculate the junction temperature under different operating conditions.

over 13 years ago

0 JasonHaedt over 13 years ago

Genius 3320 points

Here is the response to your two questions:

1.) The 0.9 C/W is for the entire chip and is worst case assuming worst case FET operation. As you would suspect, if you opened the package you would see the fets getting the hottest in this design.

2.) We are checking on the isolation question with the design team, but we do not think you need an additional isolation material. I believe we use a non-conductive die attach to tie the die to the heat slug.

Please see page 23 for additional thermal information, it does not recommend using a thermal pad and recommends using thermal grease for improved thermal performance.

0 Ryan Kehr over 13 years ago in reply to JasonHaedt

TI__Guru 55615 points

All,

For #2, the die attach material between the die substrate and the exposed PowerPAD on the top of the package is non-conductive. However, we recommend that the heat sink be attached to GND and NOT be connected to any other potential voltage in the system.

0 Brad Sundstrom over 13 years ago in reply to Ryan Kehr

Prodigy 40 points

Are there any heatsinks that you can recommend which would be compatible with the DRV8332 exposed top-side thermal pad?

0 Ryan Kehr over 13 years ago in reply to Brad Sundstrom

TI__Guru 55615 points

Brad,

We have used something like this in the past from AAVID. This is showing black anodized, but it is also available in unfinished stock. AAVID has various other extrusions as well that can be cut to a specific length. Their website is listed in the attached link.

http://www1.futureelectronics.com/doc/AAVID%20THERMALLOY/652453B01299G.pdf

You can use spacers that are the same thickness as our device to attach the heat sink.

0 Tony Philipsson over 13 years ago in reply to Ryan Kehr

Guru 12050 points

This one could work, it's the 16x16mm so the same lenght as the IC and with 3.5mm spacers on the others sides will make it stable and have gnd connection.

I would use Arctic Silver 5 Arctic Silver Thermal Epoxy to glue it down.

http://www.mouser.com/ProductDetail/Wakefield/D10650-40/?qs=VVKQmw408U8QZEW%2fTAP7wQ%3d%3d

0 John Lambert over 11 years ago in reply to Brad Sundstrom

Prodigy 50 points

Would a TO3 heatsink such as 501503B00000G work for the DRV8332? Using 3.5mm spacers and grease? Would there be too much stress on the PCB?

http://www.mouser.com/ProductDetail/Aavid-Thermalloy/501503B00000G/?qs=sGAEpiMZZMs5xvcUVeVW271ymC3Kepjw

Thanks,

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DRV8332 thermal details