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TMS320F28069M: DRV8323SRTAR interface to TMS320F28069M

Jeffrey Pacl
Prodigy 20 points
Part Number: TMS320F28069M
Other Parts Discussed in Thread: DRV8323

The DRV8323 has an enable signal that is connected to the TMS320.  When the TMS320 goes through a software update, reset,  or power-up/down condition the enable signal GPIO on the TMS320 is reconfigured as an input.  This reconfiguration allows the DRV8323 to enable.  We have the option of adding a strong pull-down on the enable signal to prevent the DRV8323 from enabling.  The concern we have is to make sure that the three phase bridge is not being activated.  Documentation for the TMS320 states that the PWM outputs are disabled during software update, reset,  or power-up/down condition.  Regardless of weather the DRV8323 is being enabled during a software update, reset,  or power-up/down condition, the three phase bridge will not activate because the PWM outputs are disabled.  Please verify our conclusion.

  • 0
    TI__Guru** 111090 points

    Yes, C2000 MCU keeps all of the I/Os including PWM and GPIO in a high-impedance state during software update, reset,  or power-up/down conditions, so you can add an external pull-down to ensure that the MOSFET gate drivers are turned off.

    Actually, the DRV8323 has internal pull-down on INx and ENABLE pins, so it's not necessary to add these external pull-down resistors on the pins of C2000.

  • 0
    Prodigy 20 points

    According to the "Hardware_Design_Guide_TMS320F28xx" the GPIO are configured as inputs with a pullup during a DSP reset.  That is why the DRV8323 enables during a DSP reset because the internal DRV8323 pulldown is not strong enough to over take the DSP internal pullup.  Not concerned that the DRV8323 enables during a DSP reset, just want to make sure that the PWM outputs are disabled, such that the DRV8323 will not activate the three phase bridge.

  • 0 in reply to Jeffrey Pacl
    TI__Guru** 111090 points

    You may select the GPIOs disabled internal pullup by default for the ENABLE pin of DRV8323. If not, you can add an external pull-down for this GPIO. The pullups on the GPIOs of PWM are are disabled by default and can be enabled through software during reset.

  • 0 in reply to Yanming Luo
    Prodigy 20 points

    The concern on the GPIO is what is their configuration up until the point that they are configured by software.  Since the PWM pins are disabled (tri-state) there is no concern that the three phase bridge will be activated by the DV8323 up until the point that the PWM pins are configured by software.

  • 0 in reply to Jeffrey Pacl
    TI__Guru** 111090 points

    The GPIO will be input and high-impedance state during reset and power-up, so it's be safety for DRV8323 even you don't add any external pull-down resistors on GPIO pins.