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drv8332 current limit

keith kuemmerle1
Prodigy 80 points
Other Parts Discussed in Thread: DRV8332

As the rating for the drv8332 is 8 amps continuous and the current limit is allowed to be set at 13 amps (for peak currents).  What limits the length of time for a 12 amp current.  Will the device safe conduct 12 amps until the thermal shut down?

  • 0
    Prodigy 135 points

    On all the DRV8xxx devices you can safely pass the rated current until TSD happens. If current is so high, however, TSD will happen fairly quick!

    Due note that all of these current parameters are heavily tied to how the device is soldered (or heat sunk) to the board. For example, if you pass 12A through the device with no heat sink whatsoever, then you would be operating on an out of spec setting and the device can suffer damage. The reason for this is that these devices require heat to be dissipated across the entire semiconductor device before the Thermal Shut down can sense the anomaly. If you develop hot spots (which can happen when there is poor heat sinking), then it is possible for the quickly rising temperature potential to wreak havoc. This is why heat sinking is so important!

    Bottom line is you want temperature to raise gradually, not instantaneously, so the TSD circuitry can catch the situation as it is intended. Notice this is the laws of physics and not a problem with the device. Any device on the planet will play by the same rules.

  • 0
    Prodigy 80 points

    Thanks, I understand the critically of good heat sinking.  When you say "pass rated current"  are you referring to the peak rated current?

  • 0 in reply to keith kuemmerle1
    TI__Guru 55615 points

    Keith,

    The peak current specified is within the acceptable limitations of what the device can safely deliver to the load without damage to the rated FETs. 

    We specify continuous as the rated current you can expect to deliver continuously with a properly sized heat sink to keep the internal junction temperature below the 150C rating in the datasheet. 

    So, you are safe up to the rated peak current, but chances are the device will go into TSD if those peaks are held for too long which is why we derate for continuous.