File:PAM2306 current limiting.png

Summary
The PWM signal on Pin 8 of a PAM2306 DC/DC converter installed in a Raspberry Pi 2. In this image, the DC/DC converter is limiting the output current by operating at a limited frequency of 600kHz. The normal operating frequency is 1.8MHz. The limited output frequency usually means that there is either a short circuit, or the PAM2306 chip is broken.