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Original question:

TLV1117LV: 4.5Vin/3.3Vout/1A application

TLV1117LV: TLV1117LV33 ,Vin=4V, Iout=600mA, Vdo=365mV is really?

ke tian
Prodigy 40 points
Part Number: TLV1117LV
Other Parts Discussed in Thread: TLV1117

like the follow picture,  I need a 3.3V, 600mA output @25℃.   if I give a Vin=4V ,can I get that result?

  • 0
    TI__Mastermind 46800 points

    Hi Ke Tian,

    This might be marginal. These are typical numbers at 500 and 800mA.  The newer TLV757 would have more margin under these conditions:

    I hope this answers your question. 

  • 0 in reply to JCHK
    Prodigy 40 points

    I know TLV757，But there are many PCB had been in stock. On that time my Vout of the power source is 4.5V. but now it had been changed to 4.0V

    Can you take a test like these conditions:Vin=4V,Iout=500 or 800mA,  then,show the really Vout to here.

    If the Vout=3.3V, I can update our BOM. and Oder it from TI.

    If the Vout=3.0V, I think TI should to correct the datasheet of  TLV1117LV33 ,Because there is not any difference with other 1117 IC.This datasheet give me  large hope to solve my question. I don't hope to get an answer is to change a new model LDO .If I can do like that, I don't need anyone to suggest me.

  • 0 in reply to ke tian
    TI__Mastermind 46800 points

    Hi Ke Tian,

    I did not realize you already had boards made up. 

    The reason that the TLV1117 differs from other 1117 Linear regulators is that it uses a PMOS as the pass element. A typical 1117 uses a Darlington pair to regulate VOUT.  See below:

    While I do not have the actual data, based on the datasheet. the effective RDSON of the PMOS in the 1117LV is ~0.7Ohm (700mV/1A). So at 800mA, the effective VDO should be ~560mV (700mOhm*800mA). This means with 4V as the input voltage you have 4V-0.56 or 3.44V which gives you 140mV of margin. This analysis is not considering the accuracy of the 4V input supply.

    I hope this helps. 

  • 0 in reply to JCHK
    Prodigy 40 points

     Thanks for your answer.

    I will to get some ICs from TI  and  test them  at the really circuit.