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Switching Boost converter drops voltage when connected to the load.


I am working on the boost converter circuit (5 to 9 Volt) and having some difficulties. Open circuit voltage is set at 10-11 Volt. At the same time, voltage drops to 4.5 Volt when connected to the 100-ohm load. I've attached some schematic and scope pictures.

Related components:
Boost IC: PAM2423 (https://media.digikey.com/pdf/Data%20Sheets/Diodes%20PDFs/PAM2421,22,23.pdf)
Inductor: PQ2614BHA-6R8K (6.8uH, +-10%, Saturation Current 34.5A)
Schottky Diode: SB240-E3/54 (Forward voltage 0.5V)

I would appreciate some help.


At a glance I would say the main problem will be the DIP-8 IC adaptor PCB. It has very thin PCB trace to connect between the IC and the 8 DIP pins on the breadboard. Secondary problem would be testing such SMPS on breadboard in general instead of layout a proper PCB according to manufacturer's recommendation.

If you are just testing the design as a quick proof of concept only, you could try soldering wires directly to PAM2423 IC pin1 for supply negative and 2,3 for supply positive. This will greatly improve the situation. However, this cannot eliminate the effect of the thin PCB traces between the power inductor connections. The best way is to solder wires also to the inductor and connect them directly to the IC pins.

Thanks a lot. Took me some time to solder all the components in the midair, but performance improved drastically.


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