I'm looking to have 4 dc-dc converters each with different outputs but one voltage input value. Vout of 9V 12V 15V and 18V. Would this chip be able to do that? enter image description here

Here is a bit from the data sheet and I believe that to change Vout all I have to do is change R4, is that correct?

Also I'm unsure of what PG, AGND and PGND are in the below picture. Could someone clarify? I know DC-DC converters separate gnd from two circuits so can AGND not connect to PGND? Below is also a link to the data sheet if that would help to answer my question. https://www.mouser.com/datasheet/2/468/RPX_1_0-1903909.pdf enter image description here


1 Answer 1


PG is power good - an output that tells you the regulator is happy. AGND (analog gnd) and PGND(power gnd) follow the datasheet’s pcb layout suggestion. This dc:dc converter is not isolated, so the gnd is not broken between the input and output. You normally pay more for isolation. Yes, select R4 for the required output voltage. You’ll need to ensure that the capacitors are suitably rated for your various voltages and heed the datasheet’s advice on layout

  • \$\begingroup\$ Is there a ideal Vin? Like ideally should Vin be higher or lower then then my planed Vouts, 21V 18V 15V 12V? I don't have much(any) experience with dc-dc converters \$\endgroup\$
    – DRC
    Commented Mar 12, 2021 at 2:50
  • \$\begingroup\$ The psu you’ve chosen is a buck device - vin must be greater than vout. Also realise that component selection and pcb layout is critical for everything to work as intended. \$\endgroup\$
    – Kartman
    Commented Mar 12, 2021 at 2:56
  • \$\begingroup\$ The only mention I see on the datasheet in regards to component selection is C12 only being used if vout is less than 2V. All the other capacitor and resistor values, except for R4, seem to be fixed and pre-defined \$\endgroup\$
    – DRC
    Commented Mar 12, 2021 at 3:43
  • \$\begingroup\$ The datasheet only gives a value for the capacitor not a part number or specification. Not all capacitors are alike. With hi-k ceramics, 10uF may not give you an actual 10uF - there’s a bit of work to determine the capacitor specs and choosing a suitable device. \$\endgroup\$
    – Kartman
    Commented Mar 12, 2021 at 3:48

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