LDL1117S50R exhibiting unstable oscillations
I am using an LDL1117S50R fixed voltage, 5 V regulator. I am regulating down from +12V to +5V. Our +12V supply is clean.
It’s a pretty simple circuit; one 1 uF capacitor at the input, and one 100 nF, one 1 uF, and one 4.7 uF capacitor at the output. I don’t need an enormous load; 500 mA is sufficient.
It was working great at first, but once I reach a load of about 200 mA, it began oscillating unstably at about 2.2. kHz. See the screenshot below. I was using a Rigol electronic load to test this.
This problem also appears to be intermittent. See the screenshots below. It’s fine, and then unstable, and then fine again, and unstable. The period of instability is not consistent.
My PCB is good. The input and output caps are close to the pins and I’ve used low ESR ceramic capacitors.
Does anyone have any idea what this may be?