Inner part of KIS-3R33S DC-DC power supply module consists of MP2307DN,which integrates adjust MOSFET.
offering 3A constant load current,exceeding the normal input voltage:4.75V-23V.
Output voltage is set to 3.33V
KIS 3R33S use DC-DC step-down IC MP2307 for controling output voltage. and have fixed output voltage of 3.33V. Modding KIS 3R33S will give us posibility to change output voltage on range of 1.84V to 20V.
Open a case and get PCB with IC out. Case can be open with tiny scrawdriver. You will get PCB like one on follow image.
First remove parts in blue and red squer.
Red one are resistors for controling output voltage, and blue one is zener diode for controling output voltage. Finaly your module will have schematic like one on follow picture:
Module is now prepare for customization. You may close module case now, all change on module is done.
Follow two schematics show two possible customization solutions :
Fixed output voltage value
Variable output voltage value
In all solution it must be add internal 3K3 resistor connected to Vadj.
For Fixed output voltage value solution standard 1% resistor value may be used like follow :
For Variable output voltage value maximal outside resistor value is 202.9K. For fixed value resistor use one of 1%.