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MCU becomes very hot & Flash API data is erased which we have saved on Flash memory

Chinmay Shah
Expert 1085 points
Other Parts Discussed in Thread: TMS320F28035, LM2575, LM3940

Dear Friends,

We are working on PMDC Motor Drive project with TMS320F28035 MCU. 

So far we were in design stage of PMDC Motor Drive.

Nowadays, we've successfully designed and completed R & D, we are testing the PMDC Drive with Elevator Auto Door Mechanism.

During testing with our Elevator Auto Door Mechanism, The MCU becomes very hot, and Flash API data is erased which we have saved on Flash memory using Flash API.
After that we've get the data by long pressing any GPIO key, and test the drive, drive is working! But still MCU gets very hot!

Please suggest the solution as early as possible. 

  • 0
    Guru 192875 points

    Hi Chinmay,

    MCU becomes very hot

    Check the health of the LDO. The overheating of working controller generally happens due to damaged LDO. Esp. check the voltage levels around the LDO and towards MCU.

    Let me know what your observations are.

    Regards,

    Gautam

  • 0 in reply to Gautam Iyer
    Expert 1085 points

    Hi Gautam,

    Thanks for quick response!

    The measured temperature for MCU is around 45 degree C, and same temperature for LDO too. Thermal Temp Sensor we've used to measure. 

    FYI: Applied excitation cycle is:

    24V AC from Transformer converted into 33V DC by a bridge rectifier,

    33V DC to LM2575 (DC to DC), 2575 gives 13V regulated DC (used for IR2133; MOSFET Driver),

    13V DC to 5V regulated DC (by using 7805, 1A),

    5V DC to 3.3V regulated DC (by using LDO LM3940, 1A).

    This regulated 3.3V DC will be applied to MCU. 

    kindly focus on the problem of Flash Memory lost too. 

  • 0 in reply to Chinmay Shah
    Guru 192875 points

    kindly focus on the problem of Flash Memory lost too.

    Chinmay, this is a clear case of device malfunctioning. Such things are experienced due to improper voltage levels towards the mcu. So please check the voltage levels around LDO thoroughly. If not LDO then I hope that none of the peripherals are damaged internally.

    Regards,

    Gautam

  • 0 in reply to Gautam Iyer
    Expert 1085 points

    Gautam,

    But after long press of Switch which I've connected to GPIO, the drive working with default parameters, then after drive working with all peripherals (QEP, PWM, ADC, GPIOs, RS232). Flash API is also working then after. 

    That means, we guess that not any peripheral is damaged!

  • 0 in reply to Chinmay Shah
    Guru 192875 points

    Chinmay, the same happened to me too. My switching regulator had gone bad and hence the voltage levels were not correct. This heated my mcu but didn't damage it while it was functioning perfectly. Replacing the regulator did the trick! So please check your hardware thoroughly.

    Regards,

    Gautam