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TPS7A4101: TPS7A4101DGNR

Nimesh Rana
Intellectual 470 points
Part Number: TPS7A4101

Tool/software:

Hello Team, 

Greetings for the day! 

We are planning to use LDO "TPS7A4101DGNR" for 10V regulation from Input supply range of 13V to 35V. We are not clear on the following statement for the total feedback resistance. Could you please eloborate more in details. If it is summation of feedback resistance value then it is not matching with design generated from TI webbench, where we can see total value of feedback resistors (R1+R2) is higher than 500E. Please help to confirm understanding to avoid issue in design. 

Your quick reply will be highly appreciated. 

Regards,

Nimesh 

  • 0
    TI__Expert 4305 points

    Hello Nimesh,

    The suggested 500 KΩ feedback resistance was calculated from the design example parameters as described in table 2. In the example, the intended output voltage is 5v. Using equation 1 as the starting point, Vout / (R1 + R2) must be equal or greater than 10 μA. Solving for (R1 + R2) with the 10 μA constraint and the 5v as the expected output, we get the 500 KΩ for the feedback network. In your design case, if you want to set your output voltage as close as possible to 10v, you can use a combination of commercially available resistors (R1 and R2) as shown in the table below. Please note that you must take into account the power dissipation thru the pass device and that the internal die temperature does not exceed 125 C. The junction to ambient thermal resistance is 66.7 C per watt, so try to maintain the power dissipation low in order to prevent thermal shutdown.

    Vout (V) R1 (Ω) R2 (Ω) Vout/(R1 + R2) (μA)
    9.9705 150000 20000 58.65
    9.984805 154000 20500 57.2195122
    9.998429 158000 21000 55.8571429
    10.01142 162000 21500 54.5581395
    9.982873 178000 23700 49.4936709
    9.958432 182000 24300 48.2716049
    9.982277 187000 24900 47.1084337
    9.959 191000 25500 46
    9.981736 196000 26100 44.9425287
    9.959517 200000 26700 43.9325843
    9.960282 215000 28700 40.8710801
    9.990449 221000 29400 39.8979592
    9.980243 226000 30100 38.9700997
    9.97999 232000 30900 37.961165
    9.978534 274000 36500 32.1369863
    9.954818 280000 37400 31.3636364
    9.962843 287000 38300 30.6266319
    9.95591 301000 40200 29.1791045
    9.956602 316000 42200 27.7962085
    9.983769 332000 44200 26.5384615
    9.976974 340000 45300 25.8940397
    9.989021 357000 47500 24.6947368
    9.964478 365000 48700 24.0862423
    9.964623 374000 49900 23.507014
    9.964761 383000 51100 22.9549902
    9.964893 392000 52300 22.4282983
    9.975842 412000 54900 21.3661202
    9.980936 422000 56200 20.8718861
    9.960559 442000 59000 19.8813559
    9.965763 464000 61900 18.9499192
    9.961249 475000 63400 18.5015773
    9.975018 487000 64900 18.0739599
    9.97491 499000 66500 17.6390977
    9.974806 511000 68100 17.2246696
    9.962097 523000 69800 16.8051576
    9.966399 536000 71500 16.4055944
    9.96268 562000 75000 15.64
    9.966774 590000 78700 14.9047014
    9.963223 604000 80600 14.5533499
    9.974055 619000 82500 14.2181818
    9.97397 634000 84500 13.8816568
    9.963727 649000 86600 13.5450346
    9.967194 665000 88700 13.2243517
    9.960822 681000 90900 12.9042904
    9.96735 698000 93100 12.5993555
    9.973577 715000 95300 12.3084995
    10.005 768000 102000 11.5
    9.964914 787000 105000 11.1714286

    Best regards,

    Daniel Esparza