Load regulation problem on isolated DC-DC converter

[ridgemao1983]

Hello:


I tried to obtain an isolated 5v voltage from main 5v input, like the picture above. But the load regulation was very poor, 5.6v at light load, 5.1v at heavy load. Although it was in accordance with the converter's datasheet(see below picture), I still wanted to decrease the voltage at light load.

Do you know how to decrease the voltage at light load? Or should I choose a different isolated DC-DC converter?



Thank you.

 

[D.A.(Tony)Stewart]

IF the design is enclosed, other than applying a constant load, 10% regulation spec means it can vary from 5.5 to 5.0 or 5.6 to 5.1 or varying 10% output from 10 to 100% load.

 

[KlausST]

Hi,

Most probably the output is not regulated yet.
It is just a square wave generator feeding a transformer input and the transformer output is rectified.

Try to use a LDO voltage regulator at the output,
or a shunt regulator ( ifyou can handle the power loss)

Klaus

 

[FvM]

It's your choice to buy a cheap unregulated or more expensive regulated DC/DC converter. LDOs with below 100 mV drop are available and should help in this case.

 

[schmitt trigger]

I would go the LDO route.

Just check the device's datasheet. Some older LDOs require as much as 600mV to maintain regulation, and have significant ground current in that state.
Newer and better LDOs can regulate with differential voltages below 100mV, and don't have such a large ground current.