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TPS543B20: Schematics Review

Shifali N
Expert 2145 points
Part Number: TPS543B20

Hi Team,

I am using TPS543B20RVFT in my design. I would like to get the circuit design get reviewed by experts. Power Requirement is as below

Vin=5V

Vout=0.84V

Iout=25A

I have connected 7numbers of 100uF capacitors at the at the regulator output. The sink side has 270uf capacitors connected to this rail. Please let me know whether this regulator can support total capacitance of 700uF+270uF.5707.Design20.pdf

  • 0
    TI__Expert 8576 points

    Hello Shifali, 

    I reviewed the schematic and it looks good to me. Attached is a excel calculator tool that can be used to check component selections as well as estimate the effect of added or removed capacitance should you ever need to check again in the future. The added 270uF should not cause any issues.

    Best regards,

    Britton

    TPS543B20_Calculator_5VIN_0p84VOUT_25A.xlsx

  • 0 in reply to Britton Jones
    Expert 2145 points

    Hi Britton,

    1. Can you please confirm the connection that I have done for RSP and RSN pins.

    A 10E resistor is connected from RSP to feedback resistor network. RSN pin is connected to GND via 10E resistor. A parallel capacitor is connected in-between RSP and RSN pins.

    2. In the schematics checklist present in the .xlsx document that you shared has the application circuit that doesn't clearly show this information.

    3. Is there any specific part package or power rating recommendation for the resistor R206. Current sense resistor connected to feedback network. Currently its 0402 package 1% tolerance and 1/16W power rating resistor.

  • 0 in reply to Shifali N
    TI__Expert 8576 points

    Hi Shifali, 

    1. Typically, we do not include the 10Ohm series resistors and a parallel capacitor on RSP/RSN. Is there a reason you want to include provisions for that? If not, I would remove the resistor on RSN and the parallel capacitor and just leave the 10Ohm resistor on the RSP path as this can be useful for stability measurements.

    2. See above

    3. I am not able to find a R206 in the schematic. Did you intend to attach a new schematic to the latest message? 

    That said, we do typically use 0402 package, 0.5% tolerance (1% is also fine), 1/16W rating for resistors in the feedback resistor network. 

    Best regards,

    Britton

  • 0 in reply to Britton Jones
    Expert 2145 points

    Hi Britton,

    1. The recommendation of 10E resistor and parallel capacitor was provided in the TI WEBENCH Designer. I have implemented the same in my design. If I consider your recommendation whether RSN pin should be directly connected to GND.

    I have also attached webench schematics design for reference.

    2. Sorry I was referring to 286 and not 206. R286 is 10E resistor connected from RSP pin to feedback resistors.

    3. The datasheet states two separate grounds AGND and PGND. But I have used single GND net for both AGND and PGND. Whether this single GND connection is correct design. Please confirm.

    3731.Design20.pdfWBDesign185.pdf

  • 0 in reply to Shifali N
    TI__Expert 8576 points

    Hi Shifali,

    Thanks for that information. I would like to make the following recommendations after further review:

    1. Please include the provisions for the capacitor between RSP/RSN and the 10E resistors. These may come in handy for filtering and/or stability measurements. 

    2. The resistor specs mentioned above are fine for R286.

    3. Please include a 0E resistor or net tie between AGND and PGND as these are individual nets.

    4. Lastly, please connect VDD to VIN using a 0E resistor or net tie, then place a 1uF decoupling capacitor as close as possible to the VDD pin. This is required as PVIN and VDD must be separate traces to satisfy layout recommendations from the datasheet.

    Best regards,

    Britton