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LNK306 5V 300mA power supply

Posted by: enkavak on Sat, 08/01/2009

Hello

I tried to use PI-Expert to obtain an output of 5V and 300mA. I constructed the schematic. At my first trial, I get nearly 4.9V. it was OK. However; I got 4.4V when I draw 150mA from the output. To resolve this, I increase the RFB resistor by 200 ohms. Then, I got 5.4V at the output when there is no load. When I tried to draw current about 150mA, output voltage decreases to 4.8V .

Also, there is some heat on the inductor and LNK306 when I draw current higher than 200mA. I mean by some heat is that enable IC to work however it is much.

-How can I resolve the problem of output voltage which I increase to obtain 5V when there is a load ?

-How can I resolve the heat problem when drawing current higher than 200mA ?

Sincerely

Engin

Comments

Submitted by sudharshana on Sun, 08/02/2009

The recommended inductor value for 5V/280mA or 5V/300mA is 680uH. the value seen in schematic is 470uH. check whether inductor is getting saturated or not.

Submitted by enkavak on Tue, 08/04/2009

Hello

Thank you for the reply.

I used PI-Expert software and it gave 470uH for the recommended iductor value. Or am I doing something wron ?

Also, how can I recognize that the inductor is saturated ?

Looking forward to hearing from you

sincerely