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TI AMC7904 Bias monitor and controller questions

Syed Mateen
Prodigy 40 points
Other Parts Discussed in Thread: AMC7904

Hi,

 

We are planning to use AMC7904 power amplifier monitor and controller chip and have following questions:

1) If we use LDMOS PA and only want to control gate and peak bias voltages with respect to temperature, then do we have to use PA_ON pin of ACM7904 power amplifier controller chip.

2) If we do not use PA_ON pin then should we ground it or leave it open

 

Thanks,

Syed

  • 0
    TI__Guru 53333 points

    Hi Syed,

    The PA_ON pin is useful for disabling the drain voltage when there is some alarm event, or during power up and shutdown events.  It is less critical in LDMOS applications (as opposed to GaN or GaAs), as the DACs will be nearly 0V.  It can still be useful if the device is detecting some other issue, like an over/under temperature limit alarm.  If you chose not to use it, you can leave the pin floating.

    Thanks,

    Paul

  • 0 in reply to Paul_Frost
    Prodigy 40 points

    Thanks Paul.

    If I do not  use remote temperature sensor, then I can still detect the temperature of the PA with internal temperature sensor right just by placing the device near PA on PCB.

    Also if I can sense the temperature with internal temp sensor then I can connect D+ and D- pins together. Can I connect the pins together as DC short or do I have to have to use some value of capacitor when I connect D+ and D- pins together. 

    Regards,

    Syed

  • +1 in reply to Syed Mateen
    TI__Guru 53333 points

    If you are not using the external temperature sense diode, you need to ground the D+ & D- pins. No cap is needed.