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TPS549D22: Difference between TPS548D22 nd TPS549D22

Part Number: TPS549D22
Other Parts Discussed in Thread: TPS548D22,

Hello expert,

May we know the difference between TPS548D22 and TPS549D22? I saw there is only PMBus signal and FSEL/ADDR difference between pinout. May we know if there is anything difference in electrical parameter for it? Customer faces TPS548D22 shortage issue and want to use TPS549D22 to replace it. Thanks a lot!

Best regards,

Ann Lien


    The TPS549D22 is functionally identical to the TPS548D22 when the same Voltage Reference, Switching Frequency, Ramp Amplitude, Current Limit, Soft-start, and Fault Response settings are selected.

    However, the TPS549D22 does not provide for Bill of Material programming of the Switching Frequency and Ramp Amplitude settings.  The TPS549D22 defaults to 650kHz switching frequency with the 1xR ramp generator and only allows this to be adjusted via PMBus.

    Designs which use the TPS548D22 that use the 19.1kΩ or 22.1kΩ FSEL to AGND, with a 100kΩ pull-up resistor will function similar with a direct replacement of the TPS549D22.  Designs which use different FSEL programming options will have changes in functionality.

    1) TPS548D22 designs which selected larger ramp amplitudes by selecting the 1/2 x R options will have higher bandwidth and could suffer from instability if they do not have sufficient output capacitance to stabilize the loop with the 1 x R ramp options.

    2) TPS548D22 designs which selected smaller ramp amplitudes by selecting the 2 x R or 3 x R options will have lower bandwidth and may not meet transient requirements.

    3) TPS548D22 designs which selected lower switching frequencies than 650kHz may suffer from increased switching losses and thermal stress.

    In designs which were previously tested with a lower switching frequency, power dissipation in the snubber resistor (Series R-C to from SW to GND) should be double checked at the new, higher switching frequency.

    4) TPS548D22 designs which selected higher switching frequencies than 650kHz may suffer reduced bandwidth or, if the original loop was highly aggressive to minimize output capacitance, loop stability limitations with the lower switching frequency.

  • Hello Peter,

    Thanks for detail reply. I attached customer' design in another post and could you kindly help to double check if we need to replace TPS548D22 with TPS549D22 what we need to change? Thanks a lot!

    Best regards,

    Ann Lien