How to choose the resistance value for MP9486 output 3.3V

DC-DC Power Converters
1

I plan to use MP9486 to output 3.3V to MCU, but I have searched for relevant information and have not found any information about the resistance values of R1 and R2. There is a formula R1=(Vout Vfb) * R2/VFb
But the information only states that when outputting 5VDC, Vfb=0.2V
What voltage should Vfb be when I want to output 3.3VDC?

2

Hi zhenglin,

Choose R1 to be 240k. Use the equation (1) in the datasheet to calculate R2. R2 should be, 15.5kOhms. Now double checking that Vfb is 0.2V, you can use a resistor divider equation:

Vfb = Vout * (R2 / (R1+ R2)) which gives around 0.19999V