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Question for LTC3309A application

I have used LTC3309A from 5Vin to 3.3Vout, Frequency:2MHz(With RT connecting to Vin for Default value), and Vout  setting for 3.3V; Sync/Mode is tied to Vin for Burst mode.

Question/Problem: I find the output voltage is dropped with the load is rised, ez: output current 0A, vout:3.3V; ouput current 1A, vout:3.25V; output current 3A, vout: 3.18V; output current 6A,

vout:3.1V.  This problem will cause my FPGA core voltage not steady and may make my FPGA broken down. Would someone help me to handle this case. Thanks.

Parents Reply


    Attached is a zip file containing the Gerber files for the layout. We do have pdf files as well but I could not load them at this time. Maybe it was to big for both on a single reply.

    The attached layout uses a 4 layer board with layer 2 a solid GND plane. There are VIN to AGND and VIN to PGND 0201 caps very close to the IC. AGND is a wider trace. AGND and PGND only connect at a single point near the output capacitor.

    I hope this helps.