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LMX2572: Pin 21

Go Bravos
Expert 6090 points
Part Number: LMX2572

Team,

Pin 21 seems to be the dedicated supply line for the RF output. Is there any issue if we don’t supply that pin but the rest of the chip is powered? I know that the buffer can be controlled by a register bit, but we have a more time precise hardware line that can enable RF output.

  • 0
    TI__Mastermind 28001 points

    Hi,

    I don't think that this ideal will work.

    The Vcc pins are connected through an ESD protection ring, so if you pull one of them low, you will forward bias some diodes on the chip.

    Also, just because we call the pin "VccBuf" and say it supplies the output buffer, it does not necessarily mean that there are no other blocks that are powered by this pin.

    Regards,

    Dean

  • 0
    TI__Mastermind 33540 points

    Hi Go,

    Pin 21 must be powered for the device to operate correctly. Operation with Pin 21 disconnected but all other supplies present is undefined behavior, and some output buffer settings may be reset between VCC cycles on that pin. LMX2572 isn't really designed for the output to start or stop on precise cycles; your best bet for something like this is an RF switch.

    Regards,