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TPS543A26: Power Section Review for TPS548A28RWWR & TPS543A26RYSR IC's

Dineshkumar R
Prodigy 80 points
Part Number: TPS543A26
Other Parts Discussed in Thread: TPS54J061, TPS548A28,

Hi,

Currently, we are designing a buck converter using TPS548A28RWWR & TPS543A26RYSR this part number for our application.

We need your support to review the design, whether it looks ok?

We are having some queries and listed below,

  1. We calculated inductor value based on a datasheet calculation (attached calculation sheet). Also, we simulated in WEBENCH power designer found values are different with respect to calculated, please suggest us for inductor value selection.
  2. We planned to use remote sensing for a 1.1V & 0.75V which, will be connected to the processor. Could you please review schematic and provide your feedback.
  3. Input and Output Capacitor value are calculated as per datasheet calculation and the same implemented in design. But in WEBENCH power designer provides lower than calculated. Can we provided based on calculated value or simulated value?

please find the TPS548A28RWWR inputs below,

Vin -12V

Vout - 0.75V

Iout - 1A

Fsw - 800KHz

Mode - FCCM

For TPS543A26RYSR Inputs,

Vin -12V

Vout - 1.1V

Iout - 7A

Fsw - 500KHz

Mode - FCCM

Thanks,

Dinesh

  • 0
    TI__Mastermind 21885 points

    I believe using a 15A device at 1A output may be confusing algorithm.   Let me check    

  • 0 in reply to David_Daniels
    TI__Mastermind 21885 points

    calculation sheet was not attached.


    0.75V

    Do you really need differential remote sense for a 1A output current?


    Are you open to using TPS54J061 for the 0.75V output.


    C670 (ss cap )should connect to VSNS- near pin 6, if using the remote sense

    R484 R483 should connect to an AGND

    C669 should connect to PGND.

    C2510 is very large.

    AGND should connect to PGND at one location.

    See 10-1 page 40 for pcb layout example.
    See figure 8-1 page 25 of datasheet for schematic example of agnd and pgnd
    www.ti.com/.../tps548a28.pdf


    Typically, inductor ripple is 10% to 40% of Iout. The tools have a range min and max inductance for control.
    When using 1A, which is


    Why use the TPS543A26 when the TPS548A28 was used for the 0.75V
    Use the TPS548A28 for the 1.1V/7A
    The pcb layout can be reused from 0.75V.
    Instead learning two devices, there is synergy when using one device for both sockets.
    Purchasing volumes will be greater when using for both sockets. Inventory is easier.


    1.1V
    On the high current supply, it is not clear you are not using the remote sense. Drawing GOSNS to the Cout
    see figure 8-1 in datasheet for schematic example


    an L of 2.2uH the equation must be incorrect in calculation. Webench estimates 1.2uH.
    Similar to webench I get 1.0uH using the equations in the datasheet.
    Use 2x100uF Cout.

    Similar feedback on Agnd and pgnd.
    R471 and R472 connects to agnd
    C639 connects to agnd
    C640 connect to pgnd.

    see figure 8-23 for pcb layout example