• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 30 subscribers
  • Views 337 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DRV8316: Operational heat Question

CHO SR
Genius 3415 points
Part Number: DRV8316

Hi,

The customer has a problem with the heat generation during DRV8316 operation.

The customer calculated thermal resistance value is 192 degrees.

TJ​ = P × RθJC​ + TC ​[℃]

(0.6A * 12V) * 15.2 + 83 = 192

Q1 : Is the customer's calculation correct?

Q2 : Calculation of thermal resistance for IC when operating under the conditions below?

* Operating conditions

1. Ambient temperature: 30 degrees

2. Load current: 0.6A

3. Motor voltage: 12V

4. Control value: 20 khz (50% duty)

5. Actual temperature measurement: 83 degrees

6. No heat sink conditions.

* Motor spec
1. Motor max current value (lock load): 5.0A

  • +1
    TI__Mastermind 26046 points

    Hi Cho,

    The calculation is almost correct, however we want to use Theta JA (junction-to-ambient) calculated from PCB layers, stackup, and copper area. Then, using power losses from the device (not motor output power) and ambient operating temperature, we can calculate the junction temperature based on the equation:

    TJ​ = P × RθJCA + TA ​[℃]

    Power losses result from slew rate, PWM frequency, motor voltage and current, and commutation scheme used. 

    We have a pre-RTM thermal calculator for Field-oriented control, which will result in more power switching losses compared to trapezoidal control. We are finalizing a calculator for trapezoidal control to accompany this. Please find the calculator attached below:

    DRV8316_FOC_Calculator_PreRTM.xlsx

    Thanks,
    Aaron

  • 0 in reply to Aaron Barrera
    TI__Mastermind 26046 points

    Also to note, we are missing some datapoints for a 2-layer board with 2 oz copper on top and bottom layers. This will show n/a as value for power losses and junction temp. Once we get Theta JA values for PCB area sizes, then FOC calculator will be complete. 

    Thanks,
    Aaron