NCP1239BD100R2G
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| Part Number | NCP1239BD100R2G |
|---|---|
| Manufacturer |
 ON Semiconductor
|
| Description | The NCP1239BD100R2G is a high-performance fixed-frequency current-mode PWM controller from onsemi, specifically developed for offline flyback power converters and energy-efficient AC-DC switched-mode power supplies. Combining high-voltage startup, current-mode regulation, frequency foldback, and comprehensive protection functions, the device provides an efficient controller solution for compact isolated power supplies. The NCP1239BD100R2G operates at a fixed nominal 100kHz switching frequency, providing an effective balance between conversion efficiency, transformer size, EMI performance, and overall power density. Its current-mode control architecture provides fast response to line and load variations while simplifying feedback-loop compensation in isolated flyback converter designs. An integrated high-voltage startup current source allows the controller to start directly from the rectified high-voltage DC rail. This architecture eliminates the need for a conventional high-loss startup resistor network and helps reduce standby power consumption while maintaining fast converter startup. For improved efficiency at reduced loads, the controller incorporates frequency foldback and skip-mode operation. The switching frequency is progressively reduced as output power demand decreases, minimizing switching losses and helping power supply designs achieve low no-load and standby power consumption. The NCP1239BD100R2G drives an external power MOSFET, allowing designers to select the switching transistor according to input voltage, output power, efficiency, and thermal requirements. This provides greater design flexibility compared with controllers that integrate a fixed power switching transistor. The device incorporates internal ramp compensation to improve current-loop stability and prevent subharmonic oscillation under operating conditions where slope compensation is required. Its current-sense architecture provides cycle-by-cycle control of the primary-side MOSFET current for reliable power conversion and overload management. Comprehensive protection functions include overload protection, overvoltage protection, brownout detection, overtemperature protection, maximum duty-cycle limitation, and current limiting. These integrated safety mechanisms help protect the power supply and connected load against abnormal operating conditions while reducing the number of external protection components required. The controller also incorporates frequency jittering, which spreads switching energy across a wider frequency range to reduce electromagnetic interference peaks. This feature can simplify EMI filter design and help finished power supplies meet applicable conducted and radiated emissions requirements. Packaged in a compact 7-pin SOIC surface-mount package, the NCP1239BD100R2G is well suited for space-constrained power supply designs and automated PCB assembly. The combination of a 100kHz switching frequency, high-voltage startup, current-mode control, low-load efficiency features, and integrated protection makes it an effective solution for modern offline flyback converter designs. The NCP1239BD100R2G is widely used in AC-DC adapters, isolated flyback converters, auxiliary power supplies, industrial power supplies, consumer electronics, networking equipment, appliance power supplies, standby power systems, set-top boxes, embedded power supplies, battery chargers, and general-purpose switched-mode power supply applications requiring efficient and reliable offline power conversion. |
| Product Group | Flyback Controller |
| MOQ | 2500 pcs |
| SPQ | 2500 pcs |
| Figure/Case | SOIC-7 |
| Package | T&R Pack |
 PDF Datasheet | |
| Ship From | Hong Kong |
| Shipment Way | DHL / Fedex / TNT / UPS / Others |
| Delivery Term | Ex-Works |
| Send RFQ | sales@signalhk.com |
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NCP1239BD100R2G
NCP1239BD100R2G