ahsan_i_h
Full Member level 5
- Joined
- May 18, 2012
- Messages
- 290
- Helped
- 80
- Reputation
- 160
- Reaction score
- 77
- Trophy points
- 1,308
- Location
- Bangladesh
- Activity points
- 3,245
There is no flaw. Quoting from an LM117/LM317 datasheet (National Semiconductor):About the flaw am I right? or may be I am thinking wrong or missing something?
That resistor (with the one from Adj pin to ground) are nominal values, picked to satisfy 2 conditions:Since the 100μA current from the adjustment terminal represents an error term, the LM117 was designed to minimize Iadj and make it very constant with line and load changes. To do this, all quiescent operating current is returned to the output establishing a minimum load current requirement. If there is insufficient load on the output, the output will rise.
Nope. Why? Because current through 220 Ω will be about 5.7 mA (1.25/220). That 5.7 mA >> 0.1 mA, so 1st condition is satisfied.For example someone came to you and ask for a variable voltage power supply circuit using LM317 . He will use this power supply circuit to test different circuits he made. Now what R1(the resistor between output and Adj) you will suggest? most probably 220 ohms. Right? Now he will make that and he may again come to you and will say that he do not get 1.2 volt as minimum at no load.
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?