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Designing Power Supplies using onsemi NCP107X series Switchers

The NCP 1076 and 1077 are High-Voltage Switchers designed for use in low power off-line Switched Mode Power supplies. They include a 700V MOSFET together with a fixed frequency current mode controller. Additional functionality includes Soft Start, Short-Circuit protection, frequency-jittering, Skip Cycle, maximum current set point together with Dynamic self-supply which negates the requirement for transformer auxiliary windings.

The Operating efficiency for different output load characteristics can be seen in the graphs below

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They will operate at 65, 100 or 130 KHz during normal operation with frequency fold back operating under light loads to provide excellent efficiency. For very light loads a skip mode is entered reducing to a very low power mode. Protection includes a timer detection function for overload or short circuit events. Overvoltage protection has automatic recovery and over temperature is also monitored for overall protection.

These devices are ideally suited for use in AC power supplies where a low cost high efficiency isolated solution is required for auxiliary applications such as white goods, utility electricity metering and similar applications.

The attached onsemi design note DN05049-D.PDF covers in greater detail the design of AC input 12 and 5V high efficiency power supplies using their NCP1076 and NCP 1077 devices.

Key features include

AC input voltage range of 85-270 V

EMI filtering and transient input protection

Secondary circuit can easily be adapted to cover different output voltage and current requirements

Click to view NCP1076 SOT RS (842-7848)

Click to view NCP1076 PDIP RS (842-7844)

Click to view NCP1077 SOT RS (842-7850_

Click to view NCP1077 PDIP RS (842-7857)

Click to view NCP431 RS (781-4386)

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