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Original question:

SN65HVD888: SN65HVD888 protection

SN65HVD888: SN65HVD888 protection

Rajan
Intellectual 270 points
Part Number: SN65HVD888
Other Parts Discussed in Thread: STRIKE

Hi,

This query is related to  "SN65HVD888 Protection" 

As per SN65HVD88 datasheet (Figure 23) suggestion we have provided protections (TVS, TBU & MOV) and tested 240VAC short circuit with respect to A and B.

As per TBU (TBU-CA-065-200-WH) datasheet it was protected from >400mA (Itrigger) Max.

Will it affect the SN65HVD888 transceiver chip? if flowing 400mA at transceiver A & B pins.

Please provide your suggestion and how much current will withstand the SN65HVD888 transceiver chip, while short circuit at A and B points. 

Thanks,

Rajan

  • 0
    TI__Guru 62910 points

    Hi Rajan,

    If the current is due to the output driving into a short circuit, the transceiver will limit it's own output current to safe levels. If the high current is due to application of a large overvoltage that triggers the device's internal transient protection circuits, then the current would only be limited by the TBU. In this case 400 mA could be tolerated for a limited duration. In my experience the TBUs trigger quickly enough that this level of current does not result in damage.

    Regards,

    Max

  • 0 in reply to Miguel Robertson
    Intellectual 270 points

    Hi Max,

    Thank you for your support,

    As you said, can you please share the SN65HVD888 Transceiver output current safe levels (Internal Transient protection circuit) detail information's for reference.

    Also let me know how much short circuit current and duration (short circuit in A and B) will withstand the SN65HVD888 transceiver chip,

    Thank You,
    Rajan 

  • 0 in reply to Rajan
    TI__Guru 62910 points

    Rajan,

    Short-circuits on A/B will result in a current no greater than 150 mA (the output current limit value of the device).  The device can survive this condition indefinitely, although depending on the ambient temperature it will likely cycle into and out of thermal shutdown due to its internal over-temperature monitor.  (This helps to ensure the device does not become damaged due to the heating associated with high power dissipation.)

    For transients it can be difficult to specify a maximum current value since the value would depend on the pulse shape of the transient (i.e., the rise/fall times, overall duration, etc.).  However, you can take a look at the test results for a given transient strike to get some idea of the amount of energy the device can withstand.  For example, the SN65HVD888 specifies being able to tolerate 12 kV ESD per IEC 61000-4-2.  This strike would have a 60-ns duration and produce a peak current of 45 A.

    Regards,
    Max