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TPS552892: schematic review

Jeff YANG
Mastermind 6275 points
Part Number: TPS552892
Other Parts Discussed in Thread: TPS552872,

Tool/software:

Hi,

I have below schematic need review and few questions as below.

  1. Input and output capacitors
  2. Inductor selection, referencing the EVM's 4.7uH inductor
  3. Compensation circuit selection, referencing the EVM
  4. Disabling the current sense function by shorting ISP/ISP together (CC# & CDC floating)
  5. Disabling DITH/SYNC by connecting them to ground
  6. Are there any other parts that you would suggest adjusting?
  7. Does TPS552872 can directly replace TPS552892? it is seems P2P but how about the comp and other component?

Thanks!

Jeff

  • 0
    TI__Expert 7780 points

    Hi Jeff,

    Thank you for reaching out. May I know what is the application here?

    1. What is the input voltage range, output voltage and output current?

    2.Can you provide part number of output caps for me to evaluate loop parameters?

    3.Is there more caps in load side? If yes, please provide quantity and part number.

    Regards,

    Mulin

  • 0 in reply to Mulin Yuan
    Mastermind 6275 points

    Hi Mulin,

    Application is SSD.

    1. Input voltage Vin=7V~14V  (typical=12V) Vout =12V, Iout = 2A

    2. 2 * 0603 or 0402 / 10uF / 25V /10% MLCC

    3. Load side also 2 * 0603 or 0402 / 10uF / 25V /10% MLCC

    Thanks!

    Jeff

  • 0 in reply to Jeff YANG
    Mastermind 6275 points

    Hi Mulin,

    Maybe can reference to below MLCC part number. thanks!

    10u,0603,SMD,+-10%,25V,X5R,GRM188R61E106KA73D,MURATA

  • 0 in reply to Jeff YANG
    TI__Expert 7780 points

    Hi Jeff,

    Is this application eSSD ? May I know more information about customer and volume?

    About the schematic, below is my feedback:

    1.Recommend to add RC snubber in SW1 and SW2. 330pF+2.2ohm.

    2.What is Isat of L19? Recommend to use Isat>8A because TPS552892 is 8A average current limit.

    3.Add a 0.1uF 0402 cap in Vout pin and put it close to IC.

    4.Only 3uF effective capacitance is left with 12V DC bias. Vout ripple will be huge and overshoot/undershoot will be huge. Recommend to add more caps. Please let me know if customer accept add more caps.

    Regards,

    Mulin

  • 0 in reply to Mulin Yuan
    Mastermind 6275 points

    Hi Mulin,

    1.Recommend to add RC snubber in SW1 and SW2. 330pF+2.2ohm.  

    • Add 330pF/50V/0402 + 7ohm/0402 in SW1 and SW2 for snubber circuit. Do you think it is okay?

    2.What is Isat of L19? Recommend to use Isat>8A because TPS552892 is 8A average current limit.

    • Isat=4A. Iout_max is only about 2A~3A.

    3.Add a 0.1uF 0402 cap in Vout pin and put it close to IC.

    • Okay.

    4.Only 3uF effective capacitance is left with 12V DC bias. Vout ripple will be huge and overshoot/undershoot will be huge. Recommend to add more caps.

    • Is it enough to use 4*22uF/25V MLCC? (GRM21BR61E226ME44L,MURATA

    Schematic modify as below:

    Is there any other suggestion to the schematic modification?

  • +1 in reply to Jeff YANG
    TI__Expert 7780 points

    Hi Jeff,

    Jeff YANG said:
    Add 330pF/50V/0402 + 7ohm/0402 in SW1 and SW2 for snubber circuit. Do you think it is okay?

    7ohm resistor will have little effect on the snubber. Customer can adjust it during test. 0402 package is too small. 1206 or 0805 is recommended.

    Jeff YANG said:
    Isat=4A. Iout_max is only about 2A~3A.

    When Vin=7V, average inductor current will reach 12*3/0.95/7=5.4A. Considering some transient occasions, recommend to use 8A inductor since TPS552892 is 8A average current limit.

    Jeff YANG said:
    Is it enough to use 4*22uF/25V MLCC? (GRM21BR61E226ME44L,MURATA

    only 15uF effective capacitance is left with 12V DC bias. Does customer have any transient overshoot/undershoot requirement? Can customer use caps with higher effective capacitance like GCM32EL8EF226KE08? 

    Regards,

    Mulin