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TPS62813-Q1: TPS62813-Q1:

user6090272
Prodigy 90 points
Part Number:

Hi Expert,

I ask 3 questions for TPS62813-Q1 operation.

Could you please support below items?

1,If the switching frequency is 1.8 to 3.5 MHz, is the inductor OK at 0.47 uH regardless of the load?

2,Is there an indication as to which setting from comp setting 1 to 3 should be selected at the start of design?
   Although the output capacitor constant differs greatly between comp setting 1 to 3,
   Does the output capacitor constant have to be changed significantly depending on the phase compensation?

3,Is it correct by the following calculation?

   Comp setting 1
   Rcf = 8.45 kΩ, fs = 18 ÷ 8.45 = 2.13 MHz

Best Regards,

Makimoto  

TPS62813-Q1
  • 0
    TI__Expert 3135 points

    Hi，

    1. 0.47uH can cover the maximum output current of our device.

    2. The compensation range has to be chosen based on the minimum capacitance used. You need to determine the output capacitance first, then choose the appropriate compensation.

    3. As the answer 2, you need to determine the output capacitance first, then choose the appropriate compensation.You can set your parameters exactly according to section 9.3.2 http://www.ti.com/lit/ds/symlink/tps62813-q1.pdf

    Best Regards,

    Kevin

    If this answers your question, Please click "This resolved my issue" button.
    ____________________________________________
    TPS62810-Q1 – New Automotive 6Vin, 2.25MHz buck family with 1% accuracy and SYNC-pin. 1-2-3-4A options.
    Smallest 2x3QFN package with wettable-flanks for optical PCB inspection

  • 0 in reply to Kevin-Cheng
    Prodigy 90 points
    Two more questions
     
    1  "Please tell us the proper inductor value under the following two conditions.
       1 Vout = 1.21 to 1.13 V
        Vin = 3.8 to 4.2 V
        Iout = MAX: 3079mA / TYP: 1500mA
         Fs = 2.025 to 2.475 MHz [with SSC]
         2 Vout = 1.44 to 1.56 V
         Vin = 3.8 to 4.2 V
         Iout = MAX: 866mA / TYP: 343.9mA
         Fs = 2.025 to 2.475 MHz [with SSC]
         Device used: TPS6281320QWRWYRQ "
    2."The first is to determine the output   capacitor value,     
        How should the capacity of the output capacitor be determined by how much the output ripple voltage is to be accommodated?
        Or can you tell me if there are other selection methods? "
  • 0 in reply to user6090272
    TI__Expert 3135 points

    determine the output   capacitor valueHi，

    1. we know that the value of inductor is related to the ΔIL(max). For example, for case1, your application allow ΔIL(max)<= 0.2 IOUT(max), you can use Equation 9 in datasheet. we get the result is 0.565uH, and you should leave some margin for inductance current, an the inductor Isat > 4A should be better. Then you can calculate case 2 by yourself. 

    2. Because our output capacitance is related to compensation, we specify the corresponding output capacitance value in table 3 and 4, you can determine the output capacitor value according the table 3 and 4.

    Best Regards,

    Kevin

    If this answers your question, Please click "This resolved my issue" button.
    ____________________________________________
    TPS62810-Q1 – New Automotive 6Vin, 2.25MHz buck family with 1% accuracy and SYNC-pin. 1-2-3-4A options.
    Smallest 2x3QFN package with wettable-flanks for optical PCB inspection

     

  • 0 in reply to Kevin-Cheng
    Prodigy 90 points
    One more question
     I think that the following two answers received before are contradictory.
    ・ Output capacitor capacity is determined according to comp setting 1 to 3 in Table 3 and Table 4
    ・ Selecting comp setting 1 to 3 is decided by the output capacitor capacity
    What I want to know is: How should I decide the output capacitor value at the start of design? "about it.
    Output capacitor capacity and comp setting 1 to 3 whichever comes first
    What kind of method should I decide on the basis?
    Hope to select comp setting 1.

     

    Best Regards,
    Makimoto  

    Best Regards,
    Makimoto  
  • 0 in reply to user6090272
    TI__Expert 3135 points

    Hi Makimoto,

    I am sorry I may not explain it clearly, the output cap is determined by Vout and the comp setting you want to choose. you want to select comp setting 1, so the value of output cap only depends on the output voltage.

    Best Regards,

    Kevin

    If this answers your question, Please click "This resolved my issue" button.
    ____________________________________________
    TPS62810-Q1 – New Automotive 6Vin, 2.25MHz buck family with 1% accuracy and SYNC-pin. 1-2-3-4A options.
    Smallest 2x3QFN package with wettable-flanks for optical PCB inspection

  • 0 in reply to Kevin-Cheng
    Prodigy 90 points
    "Thank you for your reply.
    in short
    If the output capacitor value (min value) and the output capacitor value specified in Table 3 and Table 4 are matched, which of comp setting 1 to 3 may be selected?
    (Can we recognize the example below?)
    Example
    ・ If you want to select comp setting 1
    → Select VOUT 1.2 V / Output capacitor capacity (min value) = about 32 uF
    ・ If you want to select comp setting 2
    → Select VOUT 1.2V / Output capacitor capacity (min value) = about 60uF
    ・ If you want to select comp setting 3
    → Select VOUT 1.2V / Output capacitor capacity (min value) = about 120uF
  • 0 in reply to user6090272
    TI__Expert 3135 points

    Hi,

    Your understanding is right

    Best Regards,

    Kevin

    If this answers your question, Please click "This resolved my issue" button.
    ____________________________________________
    TPS62810-Q1 – New Automotive 6Vin, 2.25MHz buck family with 1% accuracy and SYNC-pin. 1-2-3-4A options.
    Smallest 2x3QFN package with wettable-flanks for optical PCB inspection.