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DRV8803: Operating Temperature issue

Girish Joshi1
Intellectual 300 points
Part Number: DRV8803
Other Parts Discussed in Thread: DRV8860, DRV8802

Dear Sir,

We are using DRV8803 for relay driving.

When we refereed the datasheet we found that operating temperature  mentioned was –40  to 85 °C and also in Absolute maximum rating it is mentioned as Operating virtual junction temperature(Tj) –40  to 150 °C.

So which temperature we should consider kindly help us. Because we are in need of extended temperature  105 °C or 125 °C

Regards

Girish

em electronix

  • 0
    TI__Guru** 114905 points
    Hi Girish,

    How much current does the relay(s) require?
    The device can typically operate above 85C ambient, but at reduced current.

    Depending on your application there may be other devices to consider, such as the DRV8860.
  • 0 in reply to Rick Duncan
    Intellectual 300 points

    Dear Rick Duncan,

    Thanks for your reply,

    Current required by relay is only 85mA so there is no problem for usage of DRV8803. Our only concern is the operating temperature since we want use it as extended temperature of 105 Deg, C.

    Girish

  • 0 in reply to Girish Joshi1
    TI__Guru** 114905 points
    Hi Girish,

    The ratings are for higher currents. At high currents the junction temperature can increase to the point where the thermal shutdown occurs.

    At 85mA, the power is less than 2% of the rated power. The device should work with little increase in junction temperature.
  • 0 in reply to Rick Duncan
    Intellectual 300 points

    Dear Rick,

    You have said power is less than 2% of the rated power and device will work with little increase in junction temperature . Kindly specify the what is little increase temperature pl. specify the temperature

    Girish

  • 0 in reply to Girish Joshi1
    TI__Guru** 114905 points
    Hi Girish,

    Assuming the device has proper thermals, the rise in temperature at 85mA should not exceed 2C.
  • 0 in reply to Rick Duncan
    Intellectual 300 points

    Dear Rick Duncan,

    Thanks for your reply.

    Kindly tell me if all channels are ON with each channel sourcing 85mA-100mA current, what will be the overall wafer temperature(IC operating temperature) with ambient temp.

    Regards

    Girish

  • 0 in reply to Girish Joshi1
    TI__Guru** 114905 points

    Hi Girish,

    Power through the outputs at 100mA is I2R x 4, or .032W. Additional power is used to run the device and can be estimated as VM * 2.1mA.

    Assuming VM = 24V, it should be <40C, but this depends on board design and package used.

    Quick calculations can be done by going to www.ti.com/.../midlevel.tsp

    Select the DRV8802. The DRV8802PWP package has similar thermals as the DRV8803PWP thermals.

    A rough estimation for the DRV8803DW package is roughly double the PWP.