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LMZM23601EVM: About the feedback delay when the output voltage drops dynamically

Part Number: LMZM23601EVM

Hi team,

I have a question about the transition speed of Vout.

Why does it take as much as a second to reduce the output voltage if I dynamically change the feedback voltage divider resistance with "Vout Select"?

When the output voltage is raised dynamically with "Vout Select", it switches within 1 ms, but when the output voltage is lowered dynamically, it switches in about 0.1 to 1 second.

For example;

When I pulled out the jumper connector attached to 3.3V selection by "Vout select", Vout became 15V within 1ms.

However, when the jumper connector was attached to the 3.3V selection position, it took 1.3 seconds for the output voltage to drop to 3.3V.

  • Hi Ishikawa,

    The transition speed of VOUT from higher voltage to lower voltage is a result of the output capacitance discharging all of the voltage it has stored from 15V down to 3.3V. This is simply a result of the discharge characteristics of a capacitor. I would expect if you had the output loaded, the voltage may transition and decay quicker.

    Regards,

    Jimmy

  • Hi Jimmy,

    Thank you for your reply.

    I understood that the cause is only the discharge characteristics.

    Best regards,

    Takuya Ishikawa