Dear support,
I am using MP1584 in my design and unfortunately, I am unable to get it working properly. For the test, I am using Vin=5V, and R11=R12=50kOhm, thus expecting around 1.6 V on the output. However, If I connect the input voltage, I get 3 V, slowly rising to 4V, then dropping to 2V, and so on. Happens even without load present.
I tried to follow the datasheet schematic as close as possible, the only thing is the header H0, which allows me to choose between floating pin (that according to datasheet is fine and means ON) and digital output from a microcontroller.
Would you be able to provide me with some tips and support?
Load it and see what happens. Looking at the block diagram there really doesn’t seem to be anything inside the chip to hold the Vout down… So a little bit of leakage through the main switch or bootstrap charging current might lift Vout. I found the datasheet hard to read somebody had blotched “Not recommended for new designs” all over it.
Hi tomhavel.44,
Is this a new design you are working on? The MP1584 is marked not recommended for new designs, and I would suggest looking at the MP2338 instead to simplify your circuit. We offer limited support for NRFND parts to high volume companies that still use them in their designs (i.e. ongoing, not new)
What is the output current you’re trying to pull from the switcher? Did you check the current limit for your Vin power supply? Try to probe the SW and FB pins and make sure there’s no interference on these signals. Lastly, follow Pg. 12 of the datasheet to double check your COMP network values.
