The NCP1030 and NCP1031 are a family of miniature high-voltage monolithic switching regulators with on-chip Power Switch and Startup Circuits. The NCP103x family incorporates in a single IC all the active power, control logic and protection circuitry required to implement, with minimal external components, several switching regulator applications, such as a secondary side bias supply or a low power dc-dc converter. This controller family is ideally suited for 48 V telecom, 42 V automotive and 12 V input applications. The NCP103x can be configured in any single-ended topology such as forward or flyback. The NCP1030 is targeted for applications requiring up to 3 W, and the NCP1031 is targeted for applications requiring up to 6 W. The internal error amplifier allows the NCP103x family to be easily configured for secondary or primary side regulation operation in isolated and non-isolated configurations. The fixed frequency oscillator is optimized for operation up to 1 MHz and is capable of external frequency synchronization, providing additional design flexibility. In addition, the NCP103x incorporates individual line undervoltage and overvoltage detectors, cycle by cycle current limit and thermal shutdown to protect the controller under fault conditions. The preset current limit thresholds eliminate the need for external sensing components.