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TPS54561: Component difference in webench design and evaluation module design

Astha Pandey
Prodigy 70 points
Part Number: TPS54561

Hi All,

I have found component difference between webench design and EvM "SLVU993" under same input/Output voltage and current.Please provide your conformation weather I need to follow webench design or EvM design.

Webench design is attached below.webench_design_5010737_12_57633056.pdf

  • 0
    TI__Expert 4100 points
    Hello,
    Please follow EVM design.
    Regards
    Brani
  • 0 in reply to Brani Dubocanin
    Prodigy 70 points

    Hi Brani,

    Thanks for your response.

    But still my doubt is not clear that how can we get two different design for same things even both are from Texas only.

    For this i can go with EVM design but let me know for other parts whose EVM is not available. In that case we are always following WEBENCH design only. So, please update on this.

    Second thing, In datasheet it is mentioned that IC can achieve 100% Duty cycle so can I assume that it will work for 100% DUTY cycle.? In my design Input voltage can go lower than Output voltage so I am looking for 100% Duty cycle in which I can get output same as input minus drop across Mosfet Rds and Inductor Resistor.

    So, let me know if it can work with 100% Duty Cycle.

  • 0 in reply to Astha Pandey
    Prodigy 70 points

    Hi TI team, 

    Please reply for the above asked query as it is important for my use case and it is hindering me for selection of this part.

  • 0 in reply to Astha Pandey
    TI__Expert 4100 points
    Hello,
    As far as differences in component values/selection is concerned, it should be noted that many combinations of passive component values will provide for same operational point. This applies for different combinations of resistors in feedback network, as well as input /output capacitors and power inductors. When in doubt we recommend to use EVM design, since this is tested and verified design solution.

    Regarding operation at 100% duty cycle, this is described in great details in device datasheet (see sections 7.1 and 7.3.4). In case of buck regulator when input voltage is lower than output voltage care must be taken that device does not hit UVLO limit, which would case device to shut down and restart. The device current draw will significantly change. As general rule of thumb, for predictable operation of buck regulator, situation where Vin<Vout should be avoided if possible.

    Hope this helps.
    Regards
    Brani