Ncp1012: 1 W, Dual Output, Off-line Converter

This design is intended for low power applications where 5 V and/or 12 V may be necessary for control circuits in appliances or similar devices in which mains isolation is not required and low cost and simplicity are mandatory. The topology is an off-line buck converter configured for a 5 volt negative output with an additional negative 12 volt output derived from a secondary flyback winding on the buck choke. The schematic notes detail how this circuit CAN be converted for positive outputs if desired. The input section uses half-wave rectification for simplicity and allows the output common to be referenced to the mains neutral line. An input EMI Filter is provided for conducted emissions compliance. Good output cross regulation is achieved on the 12 V output with the use of stacked windings in the buck choke. Regulation feedback is achieved with a simple zener Diode and Optocoupler circuit that also provides the required offset floating for the NCP1012 controller. • Extremely simple and cost effective low power supply to provide non-isolated, low voltage outputs. • Good cross regulation due to stacked windings in the buck choke. • Low cost monolithic NCP1012 integrated controller with self-biased Vcc used for buck converter. • EMI Filter on AC input for agency compliance. • Output polarities easily reversible without component changes. • Over current protection. • 2 watt capability if NCP1014 is used for U1.
application notes                    New application notes
Download application notes and circuits


Ncp1012: 1 W, Dual Output, Off-line Converter application circuits
Ncp1012: 1 W, Dual Output, Off-line Converter application circuits



Related Electronics Part Number
Hot categories