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What is the reason for R7 in 317 regulator ?

L

little billy

Jan 1, 1970
0
Hello,

Does anyone know the 5A COnstant Volatge/Constant Current Regulator
from the LM117/LM317A/LM317 regulator, it's on page 16 and is
downloadable from

http://www.national.com/ds.cgi/LM/LM117.pdf

I am curious as to the reason from R7=220.
What will happen if we put R7=0R ?
 
C

colin

Jan 1, 1970
0
little billy said:
Hello,

Does anyone know the 5A COnstant Volatge/Constant Current Regulator
from the LM117/LM317A/LM317 regulator, it's on page 16 and is
downloadable from

http://www.national.com/ds.cgi/LM/LM117.pdf

I am curious as to the reason from R7=220.
What will happen if we put R7=0R ?

i think it sets the voltage but it looks like theyve got vout and adj pin
names transposed in that circuit.

Colin =^.^=
 
R

Rich Grise

Jan 1, 1970
0
little said:
Hello,

Does anyone know the 5A COnstant Volatge/Constant Current Regulator
from the LM117/LM317A/LM317 regulator, it's on page 16 and is
downloadable from

http://www.national.com/ds.cgi/LM/LM117.pdf

I am curious as to the reason from R7=220.
What will happen if we put R7=0R ?

It clamps the output when in constant current mode: if the load
wants to be less than 5A, the voltage wants to climb to I * R.
R7 is there to prevent that.

Rich
 
R

Roy McCammon

Jan 1, 1970
0
little said:
Hello,

Does anyone know the 5A COnstant Volatge/Constant Current Regulator
from the LM117/LM317A/LM317 regulator, it's on page 16 and is
downloadable from

http://www.national.com/ds.cgi/LM/LM117.pdf

I am curious as to the reason from R7=220.
What will happen if we put R7=0R ?

I haven't analyzed it, but I think it may be necessary
for stability. Without it, the opamp looks like it
would be driving a capacitive load.
 
R

Rok Sitar

Jan 1, 1970
0
R7 is in the circuit for Iadj. Take the time end read the instructions!
 
L

little billy

Jan 1, 1970
0
Hello my dear half baked engineers of this thread.
I am afraid you were all wrong. I wonder, shall I
tell, or shall I let you burn some more midnight
oil over this one?
 
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