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LMZM33604: larger Feed-Forward Capacitor

user5347034
Intellectual 320 points
Part Number: LMZM33604

Hello team members.

LMZM33604 uses a feed forward capacitor in parallel with RFBT. This feed forward capacitor is calculated by the equation (CFF = 4.3 × (Vout × Cout / RFBT)) near Figure 32 in the data sheet.
If I install a Feed Forward capacitor with a capacity greater than this equation, will there be problems with transient response and other issues?

  • 0
    TI__Guru 50120 points

    Hi,

    Placing a larger Cff capacitor may result in a loop gain crossover too high in frequency and the Cff phase boost contribution may be insufficient resulting in undesirable phase margin and instability. Another way to improve load transient response is by adding more output capacitance. However if you still desire to add a large Cff, I would recommend running a frequency response bode plot analysis to ensure stability with your design.

    Regards,
    Jimmy

  • 0 in reply to Jimmy Hua
    Intellectual 320 points

    Hello,Jimmy

    I understand.

    Many thanks for your help.

    Regards,