Single package pin providing soft-start and short-circuit timer functions in a voltage regulator controller

摘要

Circuits and methods for implementing both a soft-start function and a short-circuit timer function in voltage regulator controller circuits using only a single package pin are provided. The soft-start and short-circuit timer functions are performed by measuring the voltage across an external capacitor as the capacitor is charged and discharged by a function control circuit. The soft-start function is performed by charging the capacitor from a completely discharged state using a current source in the function control circuit and by using the capacitor voltage as a current limit signal to gradually increase the current drawn from a voltage source to the normal operating level. The short-circuit timer function is performed by using the charge and discharge times of the capacitor to delay the shutdown of the voltage regulator in response to a short-circuit detection.