I’m building the * DN05017/D * power supply from ON Semiconductor. This is the datasheet of the power supply with schematic and BOM So now while searching for the components, I noticed on the schematic and BOM list a resistor without a specific value; all it says is: “TBD”. Note R11 on the schematic near U1 Also Note R11! R11 is the resistor that shows “TBD” Value. And also note under the “Manufacture Part Number”, that capacitors and resistors have “TBD” but under the “Value” they have noted their specific values. Just R11 has noted “TBD”.

I’m integrating this into a AC line monitoring project.

I have googled “TBD” but can’t find my answer.

A definition I found for TBD: “time to breakdown”, but it didn’t make sense in my case, because I need the value.


What does “TBD” mean in this case? Do I have to determine the value by myself?

  • 2
    \$\begingroup\$ TBD usually means to be determined \$\endgroup\$ – Simeon R Mar 23 '18 at 19:05
  • \$\begingroup\$ Note that R11 is the "power compensation" resistor and if you search for that term, it mentions it briefly (although no guidance on how to select the value) \$\endgroup\$ – Selvek Mar 23 '18 at 19:11

From the NCP1251 datasheet, description of pin 3:

"A resistive divider from the auxiliary winding to this pin sets the OPP compensation level. When brought above 3 V, the part is fully latched off."

With no other information available, wire in a pot and dial up the resistance of R11 (aka bring down the voltage of pin 3, away from shut-off mode) until the device runs without issue under min load, max load, and when adding or removing min and max load.


TBD = To be determined.

They haven't researched that.

  • \$\begingroup\$ “R11 is output power compensation” is what the notes say under the schematic on page 2 of PDF. I searched the PDF and can’t seem to find additional notes on R11. Would it be usually a low value resistor? \$\endgroup\$ – Elizandro Peters Mar 23 '18 at 19:11

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