Onsemi NCP1239

Description

The NCP1239 is a fixed-frequency current-mode controller featuring a high-voltage start-up current source to provide a quick and lossless power-on sequence. This function greatly simplifies the design of the auxiliary supply and the VCC capacitor by activating the internal start-up current source to supply the controller during start-up, transients, latch, stand-by etc.

With a supply range up to 35 V, the controller hosts a jittered 65 or100-kHz switching circuitry operated in peak current mode control.When the power on the secondary side starts to decrease, the controllerautomatically folds back its switching frequency down to minimumlevel of 26 kHz. As the power further goes down, the part enters skipcycle while limiting the peak current that insures excellent efficiency in light load condition.

NCP1239 features a timer-based fault detection circuitry that ensures a quasi-flat overload detection, independent of the input voltage.

Features

• Fixed-Frequency 65-kHz or 100-kHz Current-Mode ControlOperation
• Frequency Foldback Down to 26 kHz and Skip Mode to Maximize Performance in Light Load Conditions
• Adjustable Over Power Protection (OPP) Circuit
• High-Voltage Current Source with Brown-Out (BO) Detection
• Internal Slope Compensation
• Internal Fixed 8-ms Soft-Start
• Frequency Jittering in Normal and Frequency Foldback Modes
• 64-ms Timer-Based Short-Circuit Protection with Auto-Recovery or Latched Operation
• Pre-Short Ready for Latched OCP Versions
• Latched OVP on VCC (NCP1239 A, B, D or E Versions)
• Latched OVP/OTP Input for Improved Robustness
• 35-V VCC Operation
• ±500 mA Peak Source/Sink Drive Capability
• Internal Thermal Shutdown
• Extremely Low No-Load Standby Power
• Pin-to-Pin Compatible with the Existing NCP1236/1247 Series
• These Devices are Pb-Free and are RoHS Compliant

Typical applications

• Offline Adapters for Notebooks and Netbooks
• AC-DC Converters for TVs, Set-Top Boxes and Printers

More information

• Datasheet
• IC product information