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AM263P4-Q1: AM263 hardware resolver to digital converter RDC questions

WhiteNoise
Prodigy 30 points

Part Number: AM263P4-Q1

1) The AM263 Technical Reference Manual states the hardware RDC has open and short detection. I see two hardware options for interfacing a resolver to the AM263, one involving op-amps and one involving a resistor divider network.
Will the open/short detection work in both these cases ? If the detection is really short and open detection I can't see how a front end with op-amps won't interfere with this. 
Does the choice of front end type then impact the safety case that has been used to provide the stated ASIL ratings ?

Links stating an op-amp front end is useable:
https://e2e.ti.com/support/microcontrollers/arm-based-microcontrollers-group/arm-based-microcontrollers/f/arm-based-microcontrollers-forum/1553276/am263p2-q1-signal-conditioning-required-or-not-for-resolver
www.ti.com/.../tidudp0.pdf
https://software-dl.ti.com/mcu-plus-sdk/esd/AM263PX/latest/exports/docs/api_guide_am263px/EXAMPLES_DRIVERS_RESOLVER_DIAGNOSITCS.html

Links stating a Resistor Divider Network is useable:
https://software-dl.ti.com/mcu-plus-sdk/esd/AM263PX/latest/exports/docs/api_guide_am263px/EXAMPLES_DRIVERS_RESOLVER_DIAGNOSITCS.html

2) Can you share access to FMEDA documentation covering the resolver, including its failure modes. In addition, it would be useful to understand which failure modes 
are addressed by each diagnostic described in the microcontroller safety manual. Is this covered in the "AM263PX-RESTRICTED-SAFETY — AM263Px restricted functional safety content"? 
I am currently awaiting download approval for this.

Thank you.

  • +1
    TI__Expert 3230 points

    Hi,

    Please find my replies below

    WhiteNoise said:
    1) The AM263 Technical Reference Manual states the hardware RDC has open and short detection. I see two hardware options for interfacing a resolver to the AM263, one involving op-amps and one involving a resistor divider network.
    Will the open/short detection work in both these cases ? If the detection is really short and open detection I can't see how a front end with op-amps won't interfere with this. 

    The OSD working is described in Section 7.5.2.16 Opens/Shorts Detection Circuit (OSDETECT) of the AM263Px Technical Reference Manual. Please do refer to the sections particularly 7.5.2.16.2 Detecting an Open Input Pin and 7.5.2.16.3 Detecting a Shorted Input Pin on how this needs to be used. The user needs to know what the expected value to be read by the S&H of the ADC, based on the particular voltage on MCU pin, driver impedance, Opens Shorts detection impedance and voltage read by the ADC.

    WhiteNoise said:
    2) Can you share access to FMEDA documentation covering the resolver, including its failure modes. In addition, it would be useful to understand which failure modes 
    are addressed by each diagnostic described in the microcontroller safety manual. Is this covered in the "AM263PX-RESTRICTED-SAFETY — AM263Px restricted functional safety content"? 
    I am currently awaiting download approval for this.

    All the FMEDA documentation is available under "AM263PX-RESTRICTED-SAFETY — AM263Px restricted functional safety content" itself. Please do refer to the same. Please do raise another e2e, if you are looking for something particular under that restricted content.

    Thanks,
    Tejas Kulakarni