I have a 5V DC input. I want to convert it into 3.3V DC. I'm trying to use VBT1-S5-S3.3-SMT DC/DC converter. I'm connecting my input to second pin of the converter. But it doesn't give 3.3V DC as output. When there is no load it gives 5V DC output on it's fifth pin. When I connect it to a circuit (when there is load) it produces different outputs. I tried couple of brand new converters, but neither of them worked. Am I doing something wrong? I can't use regulator, because the load circuit must be isolated. So Is there anything I can try?


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  • \$\begingroup\$ Please provide a schematic showing graphically how your circuit looks. The more details the better. \$\endgroup\$ – Dan Laks Sep 5 '14 at 8:21

"The converter needs a minimum of 10% loading to maintain output regulation." ie it is a 1W device so presumably you need to be drawing 100mW, or approx 30mA from the 3V3 output to get it stable.

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  • \$\begingroup\$ Try adding a 100 ohm 0.25W resistor between 3.3V and ground. It's a lot of power to waste, so if this is supposed to run from battery you probably need a different 3.3V regulator. \$\endgroup\$ – Matt B. Sep 5 '14 at 20:12

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