![]() But increasing doesn’t really help with that heavy load. It should be considered that the mains (voltage) may drop 20% so this would be catastrophic here.Īlso C1 seems a bit low for 1A design. ![]() The first graph shows the noisy and flickering power supply - and that the input voltage basically is too low for the application. Because of the very low and constant I_ADJ the exact value isn’t really important.Anyway, the 50 Ohm value is way too high, this must be a typo, i guess 50 mOhm. Thus the value may have to be similar to R_O, but this depends on the real design. The other parameter R_ADJ is a bit strange but the equivalent to R_O, only it is the ADJ - terminal. In my example I’ve set the output to 14 Volts (ratio is 2400/240), thus my R_O is set to 0.011 Ohm. However, smaller output voltages have a smaller divider ratio, thus the resulting R_O value will be less in our “well designed” (print circuit) application. And it wouldn’t help to have the LM317 and the voltage divider “close” together, when your load is at the other end of your printed circuit.Keep current traces short and wide, add copper and solder!Īssuming a good design we can estimate the Rs to be about 0.001 Ohm - But keep in mind, this is already a standard trace 2.5 mm wide and 5 mm long !!!.To reach CL’s R_O = 0.1 Ohm in the example our Rs would have to be 0.005 Ohms, which may be realistic if you connect the IC from the heat sink by long and thin wires to your printed circuit.īut even when you have about 1 inch simple PCB trace between the IC and the voltage divider this could easily reach 5 mOhms:Į.g a standard (35 um) copper trace of 25 mm length and 2.5 mm width would have about 0.005 Ohms at 40 ☌. ![]() Let’s assume the voltage divider ratio would be extreme (about 18, high output voltage, 24 Volts).
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