The NCP1395A/B includes all necessa

The NCP1395A/B includes all necessary features to helpbuild a rugged and safe switch−mode power supplyfeaturing an extremely low standby power. The belowbullets detail the benefits brought by implementing theNCP1395A/B controller:• Wide Frequency Range: A high−speed VoltageControl Oscillator allows an output frequencyexcursion from 50 kHz up to 1.0 MHz on A and Boutputs.• Adjustable Deadtime: Due to a single resistor wiredto ground, the user has the ability to include somedeadtime, helping to fight cross−conduction betweenthe upper and the lower transistor.• Adjustable Soft−Start: Every time the controllerstarts to operate (power on), the switching frequency ispushed to the programmed maximum value and slowlymoves down toward the minimum frequency, until thefeedback loop closes. The soft−start sequence isactivated in the following cases: a) normal startupb) back to operation from an off state: during hiccupfaulty mode, brown−out or temperature shutdown(TSD). In the NCP1395A, the soft−start is notactivated back to operation from the fast fault input,unless the feedback pin voltage reaches 0.6 V. To theopposite, in the B version, the soft−start is alwaysactivated back from the fast fault input whatever thefeedback level is.• Adjustable Minimum and Maximum FrequencyExcursion: In resonant applications, it is important tostay away from the resonating peak to keep operatingthe converter in the right region. Due to a singleexternal resistor, the designer can program its lowestfrequency point, obtained in lack of feedback voltage(during the startup sequence or in short−circuitconditions). Internally trimmed capacitors offer a3% precision on the selection of the minimumswitching frequency. The adjustable upper stop beingless precise to 15%.• Low Startup Current: When directly powered fromthe high−voltage DC rail, the device only requires300 A to startup. In case of an auxiliary supply, theB version offers a lower startup threshold to cope witha 12 V dc rail.• Brown−Out Detection: To avoid operation from alow input voltage, it is interesting to prevent thecontroller from switching if the high−voltage rail isnot within the right boundaries. Also, when teamedwith a PFC front−end circuitry, the brown−outdetection can ensure a clean startup sequence withsoft−start, ensuring that the PFC is stabilized beforeenergizing the resonant tank. The A version features a