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DS90UB949-Q1: FPDLINK output support "short to VBAT 36V"

Vincent Chiu
Prodigy 190 points
Part Number: DS90UB949-Q1


Hi 

Datasheet declare the DS90UB949-Q1 can detect fault conditions in the FPD-Link III interconnect with "+" & "-"  to battery short condition. The maximum battery voltage is?

Our condition is 24V battery application and follow ISO 16750-2, the battery voltage will upto 36V.

Regards,

Vincent 

  • 0
    TI__Mastermind 25765 points

    Hi Vincent,

    The serial link fault detection only detects  fault conditions. A 36V short to the FPD-Link is far beyond the recommended or absolute maximum ratings for these pins, as per the spec in the datasheet. So the "max" voltage is the max voltage of the specific pin that is shorted. Any protection against shorts to a battery needs to be implemented externally.

    Regards,

    Ben Dattilo

  • 0 in reply to Ben Dattilo
    Prodigy 190 points

    Hi Ben

    Due to FPDLINK input is serialized with AC capacitor, my understanding is the DC 36V will be blocked? And is no impact for  DS90UB949-Q1?

    Regards,

    Vincent

  • 0 in reply to Vincent Chiu
    TI__Genius 13620 points

    Hi Vincent, 

    A 36V short to the FPD-Link lines is not recommended. It will damage the DS90UB949-Q1, you would need to stepdown to a lower voltage.

    Best Regards,

    Gil Abarca

  • 0 in reply to Gil Abarca Ramos
    Prodigy 190 points

    Hi Gil

    From the datasheet 7.3.12 Serial Link Fault Detect, which declare DS90UB949 support detection of  "+" & "-" to battery short. What is the "max "battery voltage is?

    Perform short to battery  on FPDLINK DOUT0 +/- & DOUT1 +/- is follow ISO 16750-2, tp test with 36V is due to our condition is 24V car battery not 12V car battery.

    Regards,

    Vincent

  • 0 in reply to Vincent Chiu
    TI__Genius 13620 points

    Hi Vincent,

    There is two parts to your question:

    1. This feature does not have a max voltage in order to detect to a Serial Link Fault. Any voltage detected will cause this register to say that link has been lost or an error has occurred in the FPD-Link lines.

    2. Now, for protection of the chip it would depend on the AC Capacitor specs whether or not the DS90UB949-Q1 gets damaged. For example, if the AC Capacitor voltage rating is 20V and the there is 36V volts going into the capacitor it will burn and eventually damaging the device. In order to prevent this we always recommend an AC capacitor that supports double the voltage being used. The actual FPD-Link pins can not exceed 1.7V:

    Best Regards,

    Gil Abarca