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LNK3209 minimum load resistor

Posted by: treez on

Hi, We are doing a Half wave bridge rectified, 100-265vac LNK3209 buck with 24vout and 0.7A.

How much minimum load resistor do we need?

Also, we need less than 0.5w standby power.

Comments

Submitted by PI-Chloe on 04/27/2023

Hi treez, 

Thanks for using Power Integration products. 

Usually we recommend to have 3mA minimum output current as per app notes.  

With 24V output, this will be 8kohms. 

Now, you can increase the resistance (effectively decreasing the load current) but the output voltage will start to increase at the minimum load. 

If the voltage regulation is still acceptable to you, you can increase the minimum load resistor. 

Increasing load resistor will help to have a lower standby power. 

Thanks 

Regards 

PI-Chloe  

 

Submitted by PI-Chloe on 04/27/2023

Hi Treez 

Thanks for using Power Integration product. 

For a buck topology: As the load current decreases, the output voltage will increase. 

I think you are talking in adding a preload resistor. 

For the minimum load R of the preload R depends on how high the output voltage will be allowed by the designer. 

This will be an iterative process. 

Higher the Preload R will decrease the standby power but will increase the output voltage. 

Lower the Preload R will increase at standby power but will lower the output voltage. 

Meaning, there will be a trade-off. 

Thanks

Regards 

PI-CHLOE