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TPS7A02: [Asus RY ] Request for Recommended TI LDO Replacement and Clarification on Overshoot Specification

SHH
Mastermind 32196 points
Part Number: TPS7A02
Other Parts Discussed in Thread: TPS7A20

Tool/software:

Hi team,

We are currently evaluating a replacement for the AP2138N-1.5TRG1 LDO due to an overshoot issue during startup. The overshoot currently observed is exceeding Intel Panther Lake's requirement (overshoot limit: 1.575V).

Could you please recommend a suitable TI LDO alternative that closely matches the following specifications?

Output voltage: 1.5V

Output current: up to 250mA

Ultra-low quiescent current

Low dropout voltage

SOT-23-3 or similar small footprint package

Additionally, could you clarify which parameter in the LDO datasheet specifically indicates overshoot characteristics?

Do you have pin to pin IC ?

Thanks for your support.

Best regards,

Scott

  • 0
    TI__Expert 6560 points

    Hello Scott,

    There are two non-P2P recommendations here TPS7A2015PDBVR which will meet the output current spec, however the IQ will be worse at roughly 6.5uA. The other alternative would be TPS7A0315PDBVR which will not meet the output current spec, however the IQ will be much better at 200nA. 

    Now this overshoot is not really a characteristic we have since our start-ups don't tend to over shoot, quick example from TPS7A20's datasheet start-up graph below:

    There are cases where an LDO can end up in drop-out very briefly as the input is ramping up. When the LDO exits drop-out it can at times overshoot, which seems that could have happened in the scope shot provided.

    Do you know what were the other conditions here? Cin, Cout, Iout? Is the Diode out at the input of the LDO?

    Quick spec comparison here:

      TPS7A2015PDBVR TPS7A0315PDBVR AP2138N-1.5TRG1
    Iout(Max)(A) 0.3 0.2 0.25
    Vin(Max)(V) 6 6 6
    Vin(Min)(V) 1.6 1.5 2.5
    Fixed output options(V) 1.5 1.5 1.5
    PSRR @ 100
    KHz(dB)    		 60 35 -
    Noise(uVrms) 7 130 -
    Accuracy(%) 1.5 1.5 2
    Dropout voltage
    (Vdo)(Typ)(mV)    		 110 205 1000
    Iq(Typ)
    (mA)    		 0.0065 0.0002 0.001
    Output capacitor type      Ceramic Ceramic Ceramic
    Thermal resistance
    θJA(°C/W)    		 179.1 179.1 250
    Operating temperature
    range(C)    		 -40 to 125 -40 to 125 -40 to 85
    Package size: mm2 8.12 mm2: 2.8 x 2.9 (SOT-23|5) 8.12 mm2: 2.8 x 2.9 (SOT-23|5) 8.12 mm2: 2.8 x 2.9 (SOT-23|3)
    Rating Catalog Catalog Catalog
    Features Enable, Output discharge Enable, Output discharge  

    Regards,

    Andres

  • 0 in reply to Andres Sagredo
    TI__Mastermind 32196 points

    Hi Andres,

    We are reviewing the power design with RD again for VCCRTC and would like to clarify the following:


    1. The typical VCCRTC voltage is 1.5V, with a ±5% tolerance, meaning it can go up to 1.575V.

    Is this considered within spec for normal operation?

    Max current is 2mA.

    p2p is first priority, if not, then, please recommend non p2p devices.

    Please help confirm the above points. Thanks!

    Best regards,
    Scott

  • 0 in reply to SHH
    TI__Expert 6560 points

    Hi Scott,

    For both TPS7A2015PDBVR and TPS7A0315PDBVR the 1.5% tolerance takes into account line, load, and temp. So under normal operation this 5% spec should be fine. That being said, given that the max current is 2mA for the RTC, TPS7A0315PDBVR would be a good fit.

    There is no P2P for the 1.5V output option in our portfolio, hence the recommended SOT-23 5-pin alternatives here, we also have a smaller package option in a 1x1 DFN for our low IQ LDO: TPS7A0315PDQNR.

    Regards,

    Andres

  • 0 in reply to Andres Sagredo
    TI__Mastermind 32196 points

    Hi Andres,

    thanks. customer is interesting in TPS7A0215PDBVR.

    just double confirm. Can TPS7A0215PDBVR also be able to support this enquiry?

    BR,

    Scott

  • 0 in reply to SHH
    TI__Expert 6560 points

    Hi Scott,

    TPS7A0215PDBVR would also be a good fit here since it would offer even lower IQ than TPS7A0315PDBVR and will showcase a similar start-up.

    Regards,

    Andres