I am looking at a schematic design from GaN systems https://gansystems.com/wp-content/uploads/2018/10/Schematic-Prints-GS66508T-EVBDB2-180830.pdf, which uses a DC/Dc converter called https://www.mouser.co.uk/datasheet/2/468/R1DX-1710005.pdf to generate +6 and -4V from a 5V voltage input. The data sheet says the voltage is +/-5V, and the schematic uses a 6V Zener diode and a 1K resistor to split the voltage into +6/-4V.
My question is,if the output voltage is only a max of +5V, how are they generating a 6V positive rail? It is something to do with the +/- voltage generation of the converter? My second question is what is the purpose of the resistor? I understand the diode voltage gives the 6V but how do we calculate the R value to ensure -4V is generated alongside it?
My question is,if the output voltage is only a max of +5V, how are they generating a 6V positive rail? It is something to do with the +/- voltage generation of the converter? My second question is what is the purpose of the resistor? I understand the diode voltage gives the 6V but how do we calculate the R value to ensure -4V is generated alongside it?