Hi, everyone.
I will describe my problem shortly today, maybe it always was solved. Tomorrow I'll send you oscillograms, schems and other materials.
I had build ON SOLDERLESS BREADBOARD adjustable power supply exactly as it was shown in datasheet - watch "Typical application" on the first page.
For example watch here: http://lib.chipdip.ru/142/DOC000142736.pdf
It's working fine until I gave it 10Om load with 5V volts preset. I've connected osciloscope probe to leg one and instead perfect meander I saw terrible spikes and drops (will send you tomorrow).
Moreover, I see the same spikes and drops on oscilogram even without load, though LM2678ADJ gives me correct 5V output with 30kHz frequency on switch leg (pin 1).
I'll describe components shortly:
1. I'm using RLB0914-220KL as an inductor from BOURNS (I've tried RLB1314-220KL with the same result). It's maximum current output 1900mA, but as I've said before I couldn't even approach 500mA (5v output, 10Om load resistor).
2. I'm using VS-6TQ045PBF from VISHAY as a catch diode (i see that there is some difference from recomended VS-6TQ045S, so tomorrow I'll try silicone type 1N4002).
3. I've tried many different nominals as output capacitor with same result, but according to my calculations it should be 220uF/50V. And it seems it doesn't connected with switch output signal anyway.
4. I'm using 3590S-2-502L from BOURNS as an adjustable potentiometer.
5. I'm using TCL 024-124 from TRACO as input power supply (very stable 24V output).
B.R.
Constantine Laskov.
