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DRV8706-Q1: DRV8706 - ISO26262 and High Currents

Part Number: DRV8706-Q1

Hi, I'm looking to build up a full bridge to drive stator coils, VCC at 48V, current up to 60A, ideally continuous duty cycle, could go as low as 25%. Also trying to make this meet ISO 26262 ASIL B. Does the DRV8706 have supporting ISO26262 documentation, or should I look at other part numbers? Looking at the DRV8706 as a gate driver. Is it sufficient to use this one chip with the SH1, SL1, SH2, SL2 current sense to give enough redundancy for the ASIL B rating? Would I need to further divide up that current sensing into 2 separate chips (DRV8706 reads shunt 1, another ADC reads in shunt 2, MCU compares these two outputs?) Are there other gate drivers I should be looking at for this type of app?

On the FET side, suggestions for part numbers for low Rds / high current fets that could potentially handle 60A / 48V in a bridge config. I'm assuming I'd need a higher voltage rating than my nominal 48V for good design practice.

  • Hi,

    Thank you for your question. Let me review and feedback to you within 24hours.

    regards

    Shinya Morita

  • Hi David,

    The DRV8706-Q1 was not developed in ISO26262 flow, but it does have the supporting documentation to be used for Functional Safety (FMD, Pin FMA, FIT) applications with ASIL requirements. The final ASIL rating is system dependent. It will not be sufficient to use just one chip, especially DRV8706-Q1, to meet ASIL B system rating. It will rely on system architecture and/or external safety mechanisms on MCU and/or other components.

    I am unsure about your comment regarding ASIL B requiring redundancy, unless decomposition is used. For Fault Metric ASIL B is least stringent where techniques and practices like redundancy are not as common, but monitoring may be used. For ASIL C/D may require redundancy to meet.

    Do you need to always read current, or to confirm current sense integrity (relating to safety goal)?

    regards

    Shinya Morita