Post Go back to editing

LT3484-1 current limitation

I'm designing a capacitor charge circuit using the LT3484-1.  Its average current draw during charging is stated to be 225 mA however the instantaneous current can be as high as 550 mA.  If I'm looking to power this from a USB port say, where the current limit is 500 mA, is there a circuit design modification that would lower the current draw? Or another part that uses less current?  If it takes longer to charge that's not a problem, I'm just looking for a way to ease the load on my power supply.

  • eriks

    What company do you work for and what's estimated annual usage?

    Formally you can not use LT3484-1 in this application.

    Comparator A1 monitors the switch current and when the peak current reaches 1.4A (LT3484-0), 1A(LT3484-2) or 0.7A (LT3484-1)

    Thus chip will draw 0.7A, which triggers OCP of the USB controller. Supercap on the LT3484-1 input may be the obvious  solution, but you might face the same problem with OCP of the USB controller.

    You can look at flyback controller and limit peak current with the current sense resistor value.

    www.analog.com/.../11493