Thanks for the help, i figured out the problem, the capacitance i connected in the output was below 1uf, when i connected 47uF it works fine. YOurs SaRIn.... On Mon, Aug 2, 2010 at 11:25 PM, Oli Glaser wrote= : > > > -------------------------------------------------- > From: "Sarin Sukumar A" > Sent: Tuesday, August 03, 2010 7:09 AM > To: "Microcontroller discussion list - Public." > Subject: [EE]LM317 regulator output voltage fluctuation > > > I am converting 9V to 3.3V using LM317. > > But here i met a strange problem. LM317 output fluctuates with a hummin= g > > noise. > > my circuit has 3 another ICs working in this 3.3Voltage. But no one is > > getting heated. > > > > do any one know any solution to this problem? > > thanks for the help... > > YOurs SaRIn.... > > -- > > http://www.piclist.com PIC/SX FAQ & list archive > > View/change your membership options at > > http://mailman.mit.edu/mailman/listinfo/piclist > > > > Hard to say what's going on without more info really. A few questions.. > Have you tried it with the LM317 output disconnected from the rest of the > circuit to help locate where the problem actually lies? > Have you got the correct capacitance/loading on the LM317 as specified in > the datasheet? i.e is it within specifications for stable operation? > What are the other ICs in the circuit? What is it's purpose? > When you say fluctuates - how fast? Is it oscillating or just drifting? > What pitch is the humming noise? Which part of the circuit does it seem t= o > be coming from? > > > > > > > > > > > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .