I start by saying (writing actually) that this is more of a philosophical question than a problem.
I'm taking time to test ALWSR regulator which I've previously used but with CapM at the input so this time I thought I might as well leave it be and go along with the standard LM317T doing the duties as pre-reg
Strangely enough this circuit was revised with higher than normal adj-out resistor (1K for both adj-gnd and adj-out, it supposed to be more beneficial than the original 499) and even more strange in testing procedure it states no load (passing the test it will connected to the Super Regulator circuit). I thought myself 'what the heck' and tested this way with no load and the output was not the anticipated 2.5VDC but above 4VDC, which is something I was expecting. Lowering Rs below 500R or having a small load got it right.
Forgive my long introduction, here's the question: How come the version of LM317T from ST don't mind having no load with high output resistor (having 2.5VDC output) while the On Semi in question certainly does (the 317 mentioned above).
Same min load current requirements, same Adj current, same everything as fas as I can see. am I missing something ?
The datasheets:
On Semi
ST
Edit: this test is been done to a bunch of regs from both companies which are new most probably from Mouser, same result
On semis behave differently from STs.
I'm taking time to test ALWSR regulator which I've previously used but with CapM at the input so this time I thought I might as well leave it be and go along with the standard LM317T doing the duties as pre-reg
Strangely enough this circuit was revised with higher than normal adj-out resistor (1K for both adj-gnd and adj-out, it supposed to be more beneficial than the original 499) and even more strange in testing procedure it states no load (passing the test it will connected to the Super Regulator circuit). I thought myself 'what the heck' and tested this way with no load and the output was not the anticipated 2.5VDC but above 4VDC, which is something I was expecting. Lowering Rs below 500R or having a small load got it right.
Forgive my long introduction, here's the question: How come the version of LM317T from ST don't mind having no load with high output resistor (having 2.5VDC output) while the On Semi in question certainly does (the 317 mentioned above).
Same min load current requirements, same Adj current, same everything as fas as I can see. am I missing something ?
The datasheets:
On Semi
ST
Edit: this test is been done to a bunch of regs from both companies which are new most probably from Mouser, same result
On semis behave differently from STs.
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I can see that not many eye browses were lifted but I would have thrown that semi reg to the trash bin if I was in a hurry. It's the plain vanilla 317 and expected that companies will produce pretty much the same thing with different stamp on it.
Looks like you never know.
Looks like you never know.