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LM2621: Feed forward capacitor

Part Number: LM2621

To whom it may concern, I am using the LM2621 as a 5V boost converter to power another ldo regulator to 3.3V.I am having an issue with CF1 or known as the feed forward capacitor. When I do not use a feedforward capacitor I am receiving the correct voltage as an output. However, when I place the recommended 39pF ceramic cap into the circuit it gave me wild output voltages as well as eventually blew up the chip. Why is this happening? Is this due to the next to nothing esr of the cap? Should I use an electrolytic cap or tantalum cap instead?

  • Hi Steven,

    thanks for reaching out on E2E.

    Typically, a ceramic capacitor is okay for feedforward capacitor. I am thinking maybe the feedforward capacitor makes the control too fast and cause the damage. Could you kindly share the sch and layout to review? Also what is the Vin and load current?

    Best Regards,

    Eric Yue