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Part No NCP1239VDR2
Manufacturer ON Semiconductor
Catalog PMIC - AC DC Converters, Offline Switchers
Description Low-Standby High Performance PWM Controller

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Products specifications

Categories Integrated Circuits (ICs)
Manufacturer ON Semiconductor
Packaging Reel - TR
Part Status Obsolete(EOL)
Output Isolation Isolated
Internal Switch(s) No
Topology Forward
Voltage - Start Up 16.4V
Supply Voltage 11.2 V ~ 36 V
Duty Cycle 80%
Frequency - Switching Up to 250kHz
Fault Protection Current Limiting, Over Load
Control Features Frequency Control, Sync
Operating Temperature Range 0°C ~ 150°C (TJ)
Package 16-SOIC (0.154", 3.90mm Width)
Manufacturer Package 16-SOIC
Win Source Part Number 1230018-NCP1239VDR2
Manufacturer Homepage
Family Name NCP1239
Introduction Date May 02, 2005
Halogen Free Compliant
Estimated EOL Date Obsolete
Popularity Medium
Fake Threat In the Open Market 47 pct.
Supply and Demand Status Sufficient
Alternative Parts


ON Semiconductor NCP1239VDR2 Product Overview

The NCP1239VDR2 is a high-performance fixed-frequency current-mode controller designed by ON Semiconductor for high efficiency AC-DC power supplies. This product is particularly suitable for use in flyback converters, commonly found in applications such as LCD monitors, televisions, and power adapters, where efficient power conversion is essential.

Key Features

  • High-Efficiency Operation: The NCP1239VDR2 is engineered to deliver high efficiency across a wide load range, making it an ideal choice for energy-sensitive applications.
  • Fixed-Frequency Current-Mode Control: This feature provides a stable and predictable operation, reducing the risk of interference with other circuit components.
  • Frequency Foldback: To enhance efficiency at light loads, the NCP1239VDR2 incorporates frequency foldback, which reduces switching losses by lowering the operating frequency.
  • Built-in Protection Features: The device includes several protection mechanisms such as Over Power Protection (OPP), Over Voltage Protection (OVP), and Short Circuit Protection (SCP), ensuring reliable operation under adverse conditions.
  • Adjustable Overcurrent Protection: This allows designers to set the overcurrent threshold to match the requirements of their specific application, providing additional flexibility and safety.
  • Low Standby Power: The NCP1239VDR2 is designed to minimize power consumption when in standby mode, contributing to the overall efficiency of the end product.


The NCP1239VDR2 is versatile and can be used in a range of applications. It is particularly adept at powering systems that require efficient conversion of AC mains power to low-voltage DC power. The typical applications include:

  • AC-DC adapters for laptops and mobile devices
  • Power supplies for LCD TVs and monitors
  • Offline battery chargers
  • Standby and auxiliary power supplies

Quality and Reliability

ON Semiconductor is renowned for its commitment to quality and reliability, and the NCP1239VDR2 is no exception. Manufactured to high standards, this controller is designed to meet the stringent requirements of the modern power supply industry, ensuring long-term performance and dependability.

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