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The RESET for TMS320F28034PNT

John Zhang
Prodigy 130 points

All,

I use the TMS320F28034PNT in the project of solar inverter,now our customer meets the issue as below:

1、The solar panel are obscured by the cloudy or others,the voltage of output is step-down slowly from 150V to 90V,the output of LDO reduce from 3.3V to 2.8V.

2、The MCU resets agine and agine because of the VDD less voltage,the reset chip is max308,the MCU will be locked after a certain number of reset.

3、Now I want to know the belwo issue:

1)How may reset  times that the MCU will be locked?

2)How do we solve this problem of the MCU locked.

  • 0
    TI__Expert 7885 points
    Hi John,

    1. Which IC is sensing the 3.3V on the supply?
    2. What is the trip voltage at which the XRSn pin is forced low by the sensing device?
    3. Can you share this part of the schematic?
    4. If the MCU goes back to 0V, does the device become unlocked?

    Best Regards,
    Adam Dunhoft
  • 0 in reply to Adam Dunhoft
    TI__Genius 11951 points
    Hi John,
    To add to the questions Adam has asked, there is nothing in the F28034 MCU that keeps track of the number of reset and would lock out the device. If the device does not respond after a full power down and power up (Q4 above) then the device is likely damaged from using it outside the normal operating conditions or there is something else on the board preventing it from booting properly.
    Regards,
    Joe
  • 0 in reply to Adam Dunhoft
    Prodigy 130 points

    Hi Adam,

    Sorry to reply your so late.

    1. Which IC is sensing the 3.3V on the supply?

    Answer : The reset chip is MAX809,the LDO is LM1117DT-3.3/NOPB.

    2.What is the trip voltage at which the XRSn pin is forced low by the sensing device?

    Answer :There are two state,the voltage go down from 3.3V to 2.875V,MCU will be locked,if the voltage go back to 3.3V,there are two state as below:

                   1)We need to restart the power supply and the MCU will be resume to work.

                   2)No need to restart the power supply,the MCU will be resume to work.

    3.Can you share this part of the schematic?

    Answer : The waveform in the attachment..

    4.If the MCU goes back to 0V, does the device become unlocked?

    Answer : The MCU goes back to 0V,we don't know if the MCU become unlocked or not,however, the voltage go back to 3.3V, the MCU will work again(as the item#2).

  • 0 in reply to John Zhang
    TI__Expert 7885 points
    Hi John,

    Is this issue still open?

    Just to reiterate what Joe has already stated:

    "...there is nothing in the F28034 MCU that keeps track of the number of reset and would lock out the device. If the device does not respond after a full power down and power up (Q4 above) then the device is likely damaged from using it outside the normal operating conditions or there is something else on the board preventing it from booting properly."

    Do you have any signals that go to any IO pins which are active when the device supply rail is outside of the normal operating voltage range? Example: Supply is at 2.8V and an input signal on an IO pin is at 3.3V

    Best Regards,
    Adam Dunhoft