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LP38693-ADJ: LP38693-ADJ

Ivan Paulik
Prodigy 100 points
Part Number: LP38693-ADJ
Other Parts Discussed in Thread: LP38693, TPS7A49

The datasheet claims that LP38693-ADJ has noise of 0.7uV/(Hz-2). Is that number correct ?

I need low noise for analogue circuitry and I was considering LP3878MR-ADJ first.

LP38693-ADJ is cheapier, lower Iq and very low noise.

Please, confirm and/or explain, thanks.

  • 0
    TI__Mastermind 23361 points

    Hi Ivan, 

    The typical noise spec you mentioned is listed on the datasheet and but since this is a typical number, the actual noise performance may be more or less than this number but it should be close. 

    For the part recommendation, will you help to provide your Vin, Vout, Iload and noise requirement for the application? 

    Regards, 
    Jason Song

  • 0 in reply to Jason Song
    Prodigy 100 points

    Sorry, the question is different:

    For all other LDO regulators, the noise is specified in en output noise voltage (RMS) in uV(RMS).

    For LP38693-ADJ, the noise value is given in

    µV/√Hz


    Can you tell me, what is the noise in uV(RMS) for LP38693-ADJ, please ?

  • 0 in reply to Ivan Paulik
    Prodigy 100 points

    The other reason for the question is that either you have an extremely low noise or extremely low Iq. My opinion is that you cannot have both.

    For LP38693-ADJ part, the Iq is extremely low and noise value is extremely low, so I am suspicious that something is wrong.

    LP38693-ADJ is not mentioned under parts for noise sensitive applications.

  • 0 in reply to Ivan Paulik
    TI__Mastermind 23361 points

    I see your point, and LP38693 was released in 2005 and by National Semiconductor, and this is the reason the datasheet may look different than other LDO datasheet. The datasheet has no RMS noise value, and the only thing that is related to this is the noise density plot from Figure 3. 

    If you are looking for a noise-sensitive application, I would recommend considering TPS7A49 or other devices targeted for low noise applicaiton. 

    Regards, 
    Jason