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Original question:

TIDA-01418: What is the switching frequency of the IGBTs used in TIDA-01418?

TIDA-01418: Programming the microcontroller

CharliePE
Intellectual 255 points
Part Number: TIDA-01418

Hi,

My understanding of programming the microcontroller (which is controlling an inverter) is first to power off the high voltage DC bus, then to program the mictrocontroller. This is because the states of the peripherals are not determined during the programming process, and there is a chance that a shoot through can happen, unless there is external circuits to prevent this from happening.

For TIDA-01418, to re-program the MCU, we should turn off the 400V DC bus first, then program the MCU.

Is this correct?

Thanks.

  • 0
    TI__Guru** 109810 points

    It's not necessary to turn off the high voltage supply, you might stop running the motor and code, and then program the updated code directly, The MCU controller will set all GPIOs to HI-Z state without current output during the flash programming or re-load the code.

  • 0 in reply to Yanming Luo
    Intellectual 255 points

    We did this, and two switching components on one leg were burned. A shoot through happened. So during the flash programming, the PWM signals must have a high glitch on both high and low PWMs, and the PWM_En also somehow stays low (or the high impedance state on that GPIO leaves low potential and is interpreted as low signal to enable the buffer).

    Adding one pull-up resistor to pin 19 (/OE2   Net: PWM_En) of U304 SN74LVC541AQPWRQ1 will disable the buffer output if the GPIO is just left as high impedance during re-programming. This will not work if the GPIO does shortly generate a low pulse during the re-programming process. Based on your statement, this is confirmed not to be the case. Then the problem is solved.

    Another option is to add shoot-through-prevention circuit before the gate drive chips to make sure that the upper and lower PWMs will never be high at the same time.

    And at the same time, turning off the high voltage supply during flash programming will prevent shoot through damage from happening too, although it's sometimes too troublesome to do.

    Thanks.

  • 0 in reply to CharliePE
    TI__Guru** 109810 points

    You are right. In most applications, adding a buffer drive with enable pin is a generic solution, and adding a pull-up/pull-down resistor on the PWM output and the enable pins is necessary also. If these methods have been implemented on the board, the controller can be programmed more safely with the high voltage supply.

    Of course, turning off the high voltage power supply is the most safety method as you mentioned above.

  • 0 in reply to Yanming Luo
    Intellectual 255 points

    Thank you for the clarification, Yanming.