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TPS650830: Capacitor selection

Antony Lin
Genius 13480 points
Part Number: TPS650830

Hi,

For pins of VPROGOTP/VOUT3VSW, can we use capacitors of 2.2uF_0201_6.3V?

Thanks!

Antony

  • 0
    TI__Mastermind 49191 points

    Hi Antony,

     VPROGOTP is a pin for supply voltage 7V when programming OTP; it should be connected to LDO5V  in normal operation; so, 2.2uF_0201_6.3V is just ok for normal operation; since it doesn't require too much current, it's better to use a 0.1uF_0201_16V cap.   

      VOUT3V3SW is an EC domain load switch output and discharge path from LDO3V; so, 2.2uF_0201_6.3V should fine if the load on this pin no more than 100mA which is an usual case.  

    Thanks!
    Phil

  • 0 in reply to Phil Yi
    TI__Genius 13480 points

    Hi Phil,

    Thanks!   We have the same questions for VBATTBKUP/VDDIO1/VDDIO2 pins.  Can we replace the original cap (1uF/6.3 0402 X5R +/-10% ) by 1uF/6.3 0201 X5R +/20%  as shown below?

    0402 cap:

    0201 cap:

    Thanks!

    Antony

  • 0 in reply to Antony Lin
    TI__Mastermind 49191 points

    Hi Antony,

    It totally depends on how much margin with your current design. Principally, a good design doesn't have too much margin, so, the power out capacitance can't be reduced.
    The best practice is by a few experiments with a few boards in different temperatures to make sure the change is doable.

    Thanks!
    Phil

  • 0 in reply to Phil Yi
    TI__Genius 13480 points

    Hi Phil,

    Thanks!  Some more related questions as below.

     

    • Can we change VDDPG cap from “2.2uF 0402 6.3V” to “2.2uF 0201 6.3V”?
    • Is it ok to place “1uF_0201_6.3V6M” as V3P3A_RTC cap?
    • Is it ok to place “10uF_0402_6.3V6M” as LDO5V and LDO3V cap?
    • Is it ok to place “10uF_0402_6.3V6M” as VREGVR1/VREGVR2/VREGVR4/VREGVR5 and VINVR2 cap?

     

    Antony

  • 0 in reply to Antony Lin
    TI__Mastermind 49191 points

    Hi Antony,

      Please see my comments below:

    Can we change VDDPG cap from “2.2uF 0402 6.3V” to “2.2uF 0201 6.3V”? Yes, since it's a pull-up power rail, doesn't need to drive load more than 100mA.

    Is it ok to place “1uF_0201_6.3V6M” as V3P3A_RTC cap? Yes, usually RTC takes a few mA current. 

    Is it ok to place “10uF_0402_6.3V6M” as LDO5V and LDO3V cap? Yes, if they're used for PMIC power up sequence control only as its datasheet specified. 

    Is it ok to place “10uF_0402_6.3V6M” as VREGVR1/VREGVR2/VREGVR4/VREGVR5 and VINVR2 cap? Yes, since they're all connected to 5V rail, if possible, use 10V which has more margin than 6.3V; this suggestion also applys to all 5V rails mentioned above. 

    Thanks!

    Phil

  • 0 in reply to Phil Yi
    TI__Genius 13480 points

    HI Phil,

    Regarding the question about replacing the original cap (1uF/6.3 0402 X5R +/-10% ) by 1uF/6.3 0201 X5R +/20%  for VBATTBKUP/VDDIO1/VDDIO2 pins, is your major related to the accuracy of 10% vs 20% or the size of 0402 vs 0201?  Customer has some more questions as below.

    • How about using two 1uF/6.3 0201 X5R +/20%  caps to replace one 1uF/6.3 0402 X5R +/-10%?  Would it be ok?
    • How about using one MLCC 1UF/16V (0603) X5R 10% to replace one 1uF/6.3 0402 X5R +/-10%?  Would it be ok?
    • If above options are still not acceptable, please provide some reasons.

    Thanks!

    Antony

  • 0 in reply to Antony Lin
    TI__Mastermind 49191 points
    Hi Antony,
    It's more related to the accuracy of 10% vs 20%. For VBATTBKUP/VDDIO1/VDDIO2 pins are connected with 3.3V power level, so, using two 1uF/6.3V 0201 X5R +/20% caps to replace one 1uF/6.3 0402 X5R +/-10% is the best.
    Thanks!
    Phil
  • 0 in reply to Phil Yi
    TI__Genius 13480 points

    Hi Phil,

    For  VREGVR1/VREGVR2/VREGVR4, the other customer want to replace cap of 1uF/16V 0402 X5R 10% by 1uF/6.3V  0402 X5R 10%.  Would it be ok?  Or they must use 10V?

    Antony

  • 0 in reply to Antony Lin
    TI__Mastermind 49191 points

    Hi Antony,

       Since VR1=1V; VR2=1.8V and VR4(max) =1.35 V, so, no problem at all to replace cap of 1uF/16V 0402 X5R 10% by 1uF/6.3V  0402 X5R 10%.

    Thanks!

    Phil

  • 0 in reply to Phil Yi
    TI__Intellectual 2295 points

    Hi Phil,

    Customer raised a question which is wondering any concern for downsize the bootstrap cap from 0603 to 0402 in the TPS650830 design?

    Best regards,

    Randy Chen

  • 0 in reply to Randy Chen
    TI__Mastermind 49191 points

    Hi Randy,

      For the bootstrap cap selection, we recommend a 0.1-μF, size 0402, 10-V capacitor for the controllers. It is also recommended to reserve a small resistor in series with the bootstrap capacitor in case the turn on / off of the FETs need to be slowed in order to reduce voltage ringing on the switch node. This is common
    practice for controller design.

    Thanks!

    Phil

  • 0 in reply to Randy Chen
    TI__Mastermind 49191 points
    Hi Randy,

    For the bootstrap cap selection, we recommend a 0.1-μF, size 0402, 10-V capacitor for the controllers. It is also recommended to reserve a small resistor in series with the bootstrap capacitor in case the turn on / off of the FETs need to be slowed in order to reduce voltage ringing on the switch node. This is common
    practice for controller design.

    Thanks!

    Phil