System and method to limit maximum duty cycle

摘要

A system and method are disclosed to limit a maximum duty cycle and/or provide a volt-second clamp for a pulse-width modulated (PWM) signal. Depending on the circuit topology, this approach can limit the absolute duty cycle or operate as a volt-second clamp in which the duty cycle is limited as a function of a variable input control voltage, such as a line voltage. The duty cycle can be selectively programmed by setting one or more external reference components, such as one or more respective resistors. Additionally, through component matching, desired clamping can be achieved with a high level of accuracy.