Provide solution guidance to help engineers quickly locate problems and provide useful application tips
This document serves as a guide for power supply engineers to troubleshoot common issues encountered when operating Fairchild Power Switch (FPS) circuits. It covers symptoms such as failure to start, instability, voltage overshoot, and sub-harmonic oscillation, offering specific causes and solutions.
The note also includes design considerations for PCB layout, methods to improve efficiency, and application circuit diagrams for features like delayed shutdown and tight output regulation.
| Typical Vcc capacitor value for startup | 10-50uF |
|---|---|
| Typical damping resistor value for OVP | 5-20 ohms |
This problem is usually caused by too low a bandwidth in the feedback loop.
Sub-harmonic oscillation occurs when the duty cycle exceeds 50% in continuous conduction mode operation.