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MCT8316Z: OCP related/triggered fault condition

Frank Rothoff
Expert 6080 points
Part Number: MCT8316Z

Hi team,

Here a question from my customer:

Based on our initial testing the MCT8316 peak output winding current limit (IOUT) of 8A set by ILIM is a limitation for our application, can we increase voltage at ILIM to VDD/2 i.e 1.65V  by changing R10  on EVM to 10K to increase winding current considering max duty cycle of motor operation at 80% in our application.

Can share winding current waveform if required.

KR,

Frank

  • 0
    TI__Mastermind 26046 points

    Hi Frank,

    You can adjust the ILIM analog value for cycle-by-cycle limit overcurrent protection by adjusting resistors R10/R11 as shown below. 

    Currently on the EVM these values are defaulted to set the ILIM voltage to 1.25V, which is about an 8-A overcurrent limit. 

    You can use this calculator to assist with ILIM resistor divider calculations: ILIM_Calculator.xlsx

    Thanks,
    Aaron

  • 0 in reply to Aaron Barrera
    TI__Expert 6080 points

    Customer feedback:

    Thank you for clarifying, then there is no scope to increase winding current limit considering (VDD/2) –  0.4 as the minimum permissible for V_ILIM as per datasheet.

    Only if we get confirmation from your technical team, we will exceed winding current beyond 8A by setting V_ILiM to 1.05V for 12A Current Limit.

    This is wishful thinking, right?

  • 0 in reply to Frank Rothoff
    TI__Mastermind 26046 points

    Hi Frank,

    Cycle-by-cycle (CBC) current limit protection is intended for overcurrent protection over continuous operation, because the MCT8316Z absolute maximum current rating is 8-A peak. So the analog ILIM voltage that can be used to set the proportional overcurrent CBC limit is 1.65V to 1.25V for 0 to 8A, respectively. 

    For a transient overcurrent event, such as a shoot through current in the integrated FETs, the IOCP threshold is fixed at 16-A in the hardware device, or configurable to 16-A or 24-A in the SPI device. 

    Unfortunately there is no way to implement a configurable 12-A current limit in the MCT8316Z device. 

    Thanks,
    Aaron