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TMS320F28375S: Controller reset

Naveen Kumar reddy Nelavoy
Intellectual 500 points
Part Number: TMS320F28375S

Hi all,

           We are using delfino F28375s microcontroller and powered it with LM26420X ( Output L=3.3uH, C = 22uF ). When ever we try to switch on the inverter the controller is getting reset or code hangs. We were working on this issue for the past 1 week and after debugging we suspect the power supply. In the controller datasheet the working voltage levels for the controller are given but unlike earlier controllers BOR is not given in this, but when we forcefully dip 1.2 V then controller is getting reset. Can anyone suggest the behavior of the controller with power supply. We have placed code in all the ISR routines initialised by TI, but we get only NMI and ITRAP sometimes and code hangs sometimes ( Is there any other ISR with infinite loop or the code just got struck somewhere )


Note: We were also getting Memory errors sometimes when the code reaches ITRAP, but there is no problem with the code as we have tested the software when controller is powered some times. So we doubt the power supply.

  • 0
    TI__Guru 60865 points
    Hi Naveen,

    On this device there will indeed be a reset if the VDD or VDDIO rails drop significantly below the specified voltage operating range. This will occur well below the operating range (VDDIO typical trip is about 2.88V, VDD typical is about 1.10V). This trip threshold is only intended to help hold the device in reset on power-up, so you may need to use an external supply monitor if you need BOR functionality.

    If you are indeed tripping the internal reset when you start executing code this could potentially indicate that the power supply is having issues. What are the values of the 1.2V and 3.3V rails when everything is powered-up but you are not executing code? Can you see a dip in the supply voltage if you monitor the rails with a DMM? With a scope? If you statically load (using a pull-down resistor) the 3.3V and 1.2V rails with roughly the maximum rated current consumption of the C28x device, does the rail droop as read by a DMM? Are there obvious oscillations as observed by a scope?

    You may also want to check your layout and physical board:
    -Decoupling caps populated and have good solder joints
    -Correct decoupling capacitance value
    -Correct decoupling capacitor type (probably ceramic)
    -Decoupling capacitors very close to each power pin
    -Separate decoupling capacitor for each power pin
    -Power pins + decoupling capacitors are all externally connected to each other via a good power plane or good power trace
    -Check all ground connections to ground plane of switcher circuit, decoupling caps, and C28x device
    -Check that multiple ground planes are very strongly stitched together

    Some other things that could be causing a reset are the watchdog or the input clock missing clock detect. These might be good places to look next if you can't find any of the above issues with the power generation and distribution.