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I am using an LM337-N in sot-223 package. The circuit is simple, but I find the output of the circuit is ringing at a frequency about 17kHz. (I am sorry I have put a wrong image at first)
It's so annoying. I have replaced the output capacitor to a larger one, about 4.7uF, But it is still ringing. at a frequency about 6kHz.
Is there any tips in using LM337 to make it more stable?
Please note that LM337-N is a Adjustable Negative Regulator, while the LM317 is a positive voltage regulator. Two different devices.
I will presume that your question is regarding the LM317, as shown in your schematic.
For the LM317-N : A 1-μF solid tantalum, or 25-μF aluminum electrolytic, on the output insures stability. Any increase of the load capacitance larger than 10-μF will merely improve the loop stability and output impedance.
See Section '8.4.1 External Capacitors' in the LM317-N datasheet.
Low ESR ceramic type capacitors are generally not recommended for LM317 (or LM337) Cout.
Yes, the ESR is the key.
You can still use ceramic for Cout, you must add a low value resistor in series to simulate the ESR.
I would suggest 1.ohm value for the series resistor. I would also suggest increasing the 1uF ceramic value to 2.2uF, or 3.3uF, to compensate for the loss of capacitance due to applied DC voltage.
See : "Ceramic Capacitors Replace Tantalum Capacitors in LDOs " ; Document # SLVA214A