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LTC3310 not coming up

Hi,

We have following circuit converting 5V to 3.3V using LTC3310. But the output were are getting is 0.027V. We have isolated all the output side from load with same results. Any idea what we are missing here? Could not find anything wrong with the circuit. The EN pin is high and LED D18 is ON.

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  • Hi Kepco,

    What I'm seeing in your circuit is that your NAND gate inputs are left floating and this might be a problem. Can you check if the circuit works by removing the NAND logic gate and pulling the EN pin high?

    Regards,

    Jhun

  • Thanks Jhun. Totally missed it. The schematic I was first checking showed this resistor installed and EN was showing high when measured. After installing the resistor now the regulator is working but it is putting out 3.1V for some reason. It is driving few ICs on the load side. Under no load it gives 3.3V output.

  • Hi Kepco,

    How much load is the regulator sourcing? Also, I would like to suggest that the PGOOD LED source be the input voltage instead of getting it from the output. This is to ensure that only the ICs are the load for the regulator.

    You can also try using a different resistor values with a tighter tolerance of 0.1% for both the top and bottom resistors.

    Edit: Please also consider this snippet below. It's on page 15.

    Regards,

    Jhun

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  • Hi Kepco,

    How much load is the regulator sourcing? Also, I would like to suggest that the PGOOD LED source be the input voltage instead of getting it from the output. This is to ensure that only the ICs are the load for the regulator.

    You can also try using a different resistor values with a tighter tolerance of 0.1% for both the top and bottom resistors.

    Edit: Please also consider this snippet below. It's on page 15.

    Regards,

    Jhun

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