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DRV8873SEVM: DRV8873S

Ning Li
Intellectual 750 points
Part Number: DRV8873SEVM

Dears,

Customer feedback uses TI's DVR8873S chip. Eight DVR8873S chip materials are used in one product, and heat sinks are added to the front and back ends of the chips. The following tests have been carried out.

1. How to calculate the heat dissipation area of PWM100% when the chip is working at full load?

2, the product only uses one chip PWM80% output, normal output about 5 minutes later, the chip will stop output, at this time set a lower PWM can not be normal output, at this time the temperature of the infrared temperature chip is about 80℃. What is the reason to protect no output?

3. When the product uses only one chip PWM70% output, it is tested for 40 minutes and the output is normal. At this time, the temperature of the infrared temperature core is about 70℃.

The Picture 1 shows the PCBA,The picture2 shows the Cooling fin,the picture3 temp test data( the pwm is 70%).

Thanks

  • 0
    TI__Mastermind 23421 points

    Hey Ning,

    Ning Li said:
    1. How to calculate the heat dissipation area of PWM100% when the chip is working at full load?

    See 8.2.1.2 Drive Current and Power Dissipation.  You'll have no switching losses (PSW), so PTOT = PVM + PD

    Ning Li said:
    2, the product only uses one chip PWM80% output, normal output about 5 minutes later, the chip will stop output, at this time set a lower PWM can not be normal output, at this time the temperature of the infrared temperature chip is about 80℃. What is the reason to protect no output?

    The internal FET temperature of the chip might be much higher than the thermal camera is reading, though I would be surprised if it was this much higher.

    Can you periodically read the Fault Status register to see if the OTW bit is turning high, then the TSD bit turning high?  OTW is Overtemperature Warning which will signal around 150°C.  You can also set OTW_REP == 1 for OTW to be reported on the nFAULT bit.    Would like to monitor OTW and TSD to confirm that it is a thermal trip and not OCP or other fault condition. 

    Also note the device has options for Latched Shutdown vs Automatic Recovery from a TSD event.  

    See the below fault table to help determine which fault is causing your issues:

    Make sure you've done your best to follow Best Practices for Board Layout of Motor Drivers, specifically for the Thermal Pad layout.  

    Regards,

    Jacob