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TPS7A45: LDO question

Brian Zhou
Guru*** 128745 points
Part Number: TPS7A45
Other Parts Discussed in Thread: LM1086, , TL1963A, LM317

Tool/software:

Hi LDO team:

  I have few questions for LDO device, I'm looking for LDO which input is 5v-20v, output could be 3.3v or 5v. This is for type-C vbus application

for TPS7A4533, VIn is 4.3v to 20V, and output is 3.3v, any concern for overheat from 20v to 3.3v?

for LM1086,  for 3.3v output, VIn is  4.75-18V, for 5v output, VIn is 6.5v to 20V, so there is no VIn 5-20V?

Best

Brian

  • 0
    TI__Genius 12925 points

    Hi Brian,

    Is there a current rating the customer is interested in? Additionally, would the customer be okay with an adjustable device?

    Best,

    Hannah

  • 0
    TI__Genius 12925 points

    Hi Brian,

    For the TPS7A4533 device, the concern with dropping from 20V to 3.3V with this device would be thermals. If using the maximum output current of 1.5A and the DCQ package, the thermals would damage the device. Using a current of less than 250mA, could increase thermals to 208.75 deg C. For the DCQ package, the customer would want to consider a lower load current when using this device. For the KTT package and an output current of 250mA, the thermals could increase as much as 116 degrees, which may be a better fit for this application if the customer is okay with the KTT package. 

    For the LM1086 device, it does look like the only device that can handle a 20V input would be the 5V option.

     

    We validate our measurements across these parameters, so I would not necessarily increase the input.

    Would the customer be okay with a 5V output option?

    Please let me know your thoughts when you have a moment, and we can move from there.

    Hope this helps.

    Best Regards,

    Hannah

  • 0 in reply to Hannah Grace
    TI__Guru*** 128745 points

    Hi Hannah: 

         For USBC VBus, it could be 5v or 20v, So I need Vin can support 5v-20v. for 5v output of LM1086, Vin is 6.5v-20v, not 5v.

         Yes, I can use  adjustable device, any suggestion?

      What I need is Vin  5-20v, output can be 3.3v, 5v or 12v, Current >1A.

    Best

    Brian

       

  • 0 in reply to Brian Zhou
    TI__Genius 12925 points

    Hi Brian, 

    I have just reached out to our marketing engineer and will let you know what feedback they can provide on a part recommendation.

    Thank you for your patience.

    Best Regards,

    Hannah

  • 0 in reply to Brian Zhou
    TI__Genius 12925 points

    Hi Brian,

    This is what our marketing engineer sent back as suggestions:

     

    TPS7A45

    LM1086

    TL1963A

    LM317

    Iout(Max)(A)

    1.5

    1.5

    1.5

    1.5

    Vin(Max)(V)

    20

    29

    20

    40

    Vin(Min)(V)

    2.1

    2.6

    2.1

    3

    Vout(Max)(V)

    20

    27.5

    20

    37

    Vout(Min)(V)

    1.5

    1.25

    1.2

    1.25

    Fixed output options(V)

    1.5, 1.8, 2.5, 3.3

    1.8, 2.5, 3.3, 5

    1.5, 1.8, 2.5, 3.3

    ---

    PSRR @ 100
    KHz(dB)

    38

    30

    45

    38

    Noise(uVrms)

    35

    38

    40

    38

    Accuracy(%)

    2.5

    2

    3

    5

    Dropout voltage
    (Vdo)(Typ)(mV)

    300

    1300

    340

    2000

    Iq(Typ)
    (mA)

    1

    2

    1

    5

    Output capacitor type    

    Ceramic

    Non-Ceramic

    Ceramic

    Non-Ceramic

    Thermal resistance
    θJA(°C/W)

    28

    23

    33

    24

    Operating temperature
    range(C)

    -40 to 125

    0 to 125, -40 to 125

    -40 to 125

    0 to 125

    We do not have any other devices besides these that fit the customer's specifications.

    Hope this helps!

    Best,

    Hannah