I am using this circuit to power some test equipment. The circuit is divining leds and voltage dividers. As the load increases it appears to be going to zero volts on the output. The load never goes above 300mW. It is rated for 3.3W output so I would think it would work. But it is not.



Two possibilities that come to mind are activation of the device’s thermal protection, and insufficient output capacitance.

The effective capacitance of ceramic capacitors tends to drop significantly with applied DC bias, with the effect generally getting worse as more C gets packed into a smaller package. A 25V/10uF X5R in an 0603 package might only provide 5uF or so at 3.3V, which could result in the device becoming unstable.

And of course, being a linear regulator if your source for the input can’t supply the required current, that would be a problem…

Scoping the input & output to see what the actual waveforms are might help shed some additional light on what’s happening.