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LMZ10504

Jeramie Bianchi
Expert 3315 points

Hi,

So from my understanding on page 13 of the datasheet, when using this part you want the EN input to be either based off the input voltage or output voltage. There is no reason to have the EN pin turned on before the input to the IC.

My question: Is it true that if the EN pin goes high before the input voltage, that the chip can burn up from this?

Regards,

Jer

  • 0
    TI__Mastermind 23091 points

    well,

    EN & PGOOD pins, when present, are used to properly program the start-up sequence of the rails ramp-up in system that share a power (VIN) bus.

    sometimes, depending on package, these pins are not always present. PGOOD is less frequently present so, when a controller that should enable another one, then a divider on VOUT can be used: this scheme is the example you looked at page 13 of the device datasheet.

    in this, VIN is the shared power bus, meaning it is assumed to be present (the sequencing refers to VOUTx).

    while the scenario in which EN ramps-up before VIN is, regardless the sequencing scheme, a wrong (unwanted) situation.

    Vincenzo

  • 0
    TI__Intellectual 1160 points

    Hello Jeramie,

    Although it is not a typical situation, the EN pin can be on before VIN and cause no damage.

    If this was not allowed, it would be described in the abs max section of the datasheet that EN voltage cannot be >VIN.

    Regards,

    Allan