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TPS546D24A: The methods and components library of the optimal BOM list

Shane Lai
Prodigy 40 points
Part Number: TPS546D24A

Hi,

In the TI power designer, I have found that this tool can support four optimization orientations. I would like to know the methodology behind small footprint, low cost, balanced, and high-efficiency designs.

As far as I am aware, the small footprint design is based on a higher switching frequency, while the high-efficiency design is based on a lower switching frequency. For the low-cost design, is the target to only adopt low-cost components? Additionally, what is the method for achieving a balanced design?

This tool also provides a BOM list, with each component having its price. Is the price based on purchasing a very high quantity? Or what’s the price based on?

The alternative part selection lists various components of the same type. I believe there is a component library built into the website. Can these component libraries be shared with us, such as capacitors, inductors, resistors, MOSFETs, SPS, etc.?

  • 0
    TI__Genius 11316 points

    Hi Shane,

    I will reach out to the TI power designer team to verify the details, and I'll provide you with an update by tomorrow.

    Thank you for your patience.

    Tomoya

  • 0 in reply to Tomoya Ide
    Prodigy 40 points

    Hi Tomoya,

    Thank you for your prompt attention to this matter. I appreciate your willingness to verify the details with the TI power designer team. I look forward to receiving your update by tomorrow. Thank you for your assistance and patience.

  • +1 in reply to Shane Lai
    TI__Genius 11316 points

    Hi Shane,

    Please see below the response to your questions. 

    Shane Lai said:

    As far as I am aware, the small footprint design is based on a higher switching frequency, while the high-efficiency design is based on a lower switching frequency. For the low-cost design, is the target to only adopt low-cost components? Additionally, what is the method for achieving a balanced design?

    A) Yes, overall target is to achieve low cost design with given input condition. But keeping fsw between EVM frequency and highest possible frequency and the increasing weight for low cost components for selection (in weighted sort algorithm) also helps in achieving the lost cost designs.

    B) Balanced designs are achieved by keeping the fsw same as EVM frequency

    Shane Lai said:
    This tool also provides a BOM list, with each component having its price. Is the price based on purchasing a very high quantity? Or what’s the price based on?

    A) For IC, price is based on 1KU. This we can verify in export tab of the design as well. E.g. for TPS546D24A

    B) For passive components the prices displayed are UNIT PRICE for Maximum order quantity mentioned by the distributor (Basically lowest unit price). Please note that currently Webench has vendor from which we fetch our prices of passives. But it may not be always latest prices. Customer may have to go to digikey (or any other distributor)  and get prices for required quantity.

    E.g. For CSR1206FT1R00 → Webench displays $0.04

    Shane Lai said:
    The alternative part selection lists various components of the same type. I believe there is a component library built into the website. Can these component libraries be shared with us, such as capacitors, inductors, resistors, MOSFETs, SPS, etc.?

    Yes, Webench has huge database of passives (which include part numbers and their electrical characteristics values). TI had a team who added these in Webench database over the period of time. Internally Webench team has access to the whole database, but we do not share this with external users. 

    Please get back to us if you have further queries.

    Thank you,
    Tomoya

  • +1 in reply to Tomoya Ide
    Prodigy 40 points

    Hi Tomoya,

    Thank you for your reply.

    For the optimal method, could you help me to check my comments or questions as follows?

    1. Low cost design: 

    Calculate the total cost for each switching frequency and identify the case with the lowest cost.

    2. Balanced design:

    Set the switching frequency to match the EVM's switching frequency value. However, consider how to choose components with varying costs and footprint sizes.

    3. Small footprint design:

    Set the switching frequency as high as possible and choose components with the smallest footprint size.

    4. High efficiency design method:

    Set the switching frequency as low as possible. Select components with the lowest power loss, such as the inductor and capacitor with the lowest ESR, and the MOSFET with the lowest Ron.

  • 0 in reply to Shane Lai
    TI__Mastermind 32360 points

    Hello Lai, 

    Tomoya is out today, what you listed above is correct. 

    The only comment I have is on the Inductor has major loss factor when choosing high DCR. Lower DCR inductor are typically more expensive and bigger in size. this is the major cost/size/efficiency trad off you can make. COUT and how much you need depends on the VOUT ripple and transient response. 

    efficiency vs fsw losses.pdf  

    Thanks! 

    Tahar