Setting the voltage converter ST1S40 output voltage +5V


I found linear DC/DC voltage converter for power (IN +12V / OUT +5V) - ST1S40. This conventer needed me for power my board created with basic chip of ATMEGA328.

Basic features:

  • Input Voltage: 4V-18V
  • Output Voltage: 0.8V-18V
  • Max output current: 3A
  • High efficiency


I think that output voltage regulation with resistors. I do not understand how to calculate the value of resistor for output voltage +5V :frowning:

In Datasheet:

Has anyone worked with this converter?

You match the output of the voltage divider to the vref voltage (5v -> 0.8v).

20 / (105 + 20) * 5 = 0.8

R1 = 105K and R2 = 20K for 5 volt output.


Thank you!!!