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Original question:

DRV8803: Operating Temperature issue

DRV8803: DRV8803

tim jackson1
Prodigy 40 points
Part Number: DRV8803

We are looking to confirm that the DRV8803 is capable of supplying power for continuous operation at an ambient temp of 40 C.  The gate driver will be supplying 24VDC with the following current requirements on each channel:
ch1: 560 mA
ch2: 50 mA
ch3: 5 mA
ch4: 5 mA

Thank you!

-T

  • 0
    TI__Expert 8985 points
    Hi Tim,

    To clarify, is that current RMS or peak?
  • 0 in reply to Hector Hernandez Luque
    Prodigy 40 points

    These are the nominal operating currents. There will be spikes above the larger one as it's an inductive load (solenoid valve), but they should be short.

    Best,

    T

  • 0 in reply to tim jackson1
    TI__Expert 8985 points
    Hey Tim,

    If you look at the Electrical Specifications, you will find that the device on package SOIC, can handle 0.8 A continous current per channel when all channels are on. Device on package HTSSOP can handle up to 1 A continous current.
  • 0 in reply to Hector Hernandez Luque
    Prodigy 40 points
    Hi Hector,

    Thank you for the reassurance. Yes I noted that in datasheet before posting here, but the topic of Thermal Information is the area of concern. This device will need to operate continuously at 40C ambient, and noting the many thermal metrics it was a bit difficult to understand how this device current affects the temperature with respect to ambient temperature. I realize 40C is well below the spec'd operating range, but am looking for confirmation on this.

    Best,
    T
  • 0 in reply to tim jackson1
    TI__Expert 8985 points
    Hi Tim,

    Thank you. I had forgotten about the 40 C comment in the original post. I will verify tomorrow and get back to you.
  • 0 in reply to Hector Hernandez Luque
    TI__Expert 8985 points
    Hi Tim,

    We can see that the package with no thermal pad (SOIC) has a Junction-to-ambient thermal resistance of 67.7 C / W (let's take this package as an example since it has the largest magnitude of the parameter between both packages). The Rdson of the FETs is around 850 mOhms at 125 C (worst case Rdson).

    Given you are operating 620 mA when all channels are on, the calculation for the consumed wattage if the FETs were operating in highest temperature will be 620 mA ^ 2 * 850 mOhms = 0.33 W.

    To calculate the junction to ambient temperature increase in that worst-case scenario for the given current 620 mA: 0.33 W * 67.7 C/W = 22.34 C.

    Therefore, we can conclude that, if your application has an ambient temperature of 60 C and the FETs are operating at the worst case Rdson, the driver would have a junction temperature of increase of 22.34 C to 88.34 C, below the max operating temperature of 125 C.
  • 0 in reply to Hector Hernandez Luque
    Prodigy 40 points

    Hi Hector,

    Thank you for the sample calculations. This is helpful and looking at your calculations for 60 C makes me feel safe using this product in a maximum 40 C environment.

    Best,

    Tim