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XL4N29 Photodarlington: Switching Power Supply Feedback Isolation

The XL4N29 is a photodarlington optocoupler from International Rectifier, designed for signal isolation and feedback in switching power supplies. This article provides a detailed technical overview of its specificatio...

XL4N29 Photodarlington: Switching Power Supply Feedback Isolation

📌 Product Overview

The XL4N29 is a high-performance photodarlington optocoupler manufactured by International Rectifier. It provides electrical isolation between input and output circuits while enabling signal transmission. Designed for robust operation, it is primarily used in feedback control loops for switching power supplies and in applications requiring isolation between main and control circuits. Its key focus is ensuring stable system performance and reliable fault signal transmission.

⚙️ Typical Applications

  • Switching power supply feedback and isolation
  • Photovoltaic energy storage systems
  • Industrial automation control and PLC interfaces
  • Motor control and relay drive circuits
  • Data collection and inverter control
  • Communication and digital circuits for high-frequency signal transmission

🔬 Key Technical Specifications

ParameterSymbolValueUnitCondition
Current Transfer RatioCTR100 (min)%IF=10mA, VCE=10V (4N29)
Isolation VoltageViso5000Vrms
Operating TemperatureTOPR-55 to 100°C
Forward VoltageVF1.2 (typ)VIF=10mA
Collector-Emitter Saturation VoltageVCE(sat)1 (max)VIF=8mA, IC=2mA
Turn-On TimeTon5 (max)µsVCE=10V

⚠️ Absolute Maximum Ratings & Process Limits

ParameterSymbolValueUnit
Forward CurrentIF60mA
Collector CurrentIC100mA
Collector-Emitter VoltageVCEO30V
Power DissipationPD100mW
Operating TemperatureTOPR-55 to 100°C
Soldering TemperatureTSOL260°C (for 10s)

📦 Package, Dimensions & Assembly Notes

The XL4N29 is available in two standard packages: DIP6 (through-hole) and SMD6 (surface mount). The DIP6 package uses matte tin-plated leads, compliant with MIL-STD-202 Method 208 for solderability. For SMD6 assembly, reflow soldering is recommended with a peak temperature not exceeding 260°C. The device features a UL 94V-0 rated molding compound, ensuring high flame resistance for safe operation in various environments.

🚀 Sourcing & Supply Considerations

  • Ordering Codes: Specify package type (DIP6 or SMD6) and halogen-free options.
  • Packaging: DIP6 versions are shipped in tubes (65 pcs), while SMD6 versions are on tape and reel (1000 pcs).
  • Authenticity: Verify supplier channels to ensure compliance with CQC, UL, and VDE standards.
  • Sample & Volume: Contact technical support for sample requests and volume production lead times.

❓ FAQ

Q: What is the difference between the XL4N29 and XL4N33?
A: The primary difference is the Current Transfer Ratio (CTR). The XL4N29 has a minimum CTR of 100%, while the XL4N33 offers a higher minimum CTR of 500%, making it suitable for applications requiring greater signal amplification.

Q: What is the isolation voltage rating of the XL4N29?
A: The isolation voltage (Viso) is rated at 5000 Vrms, providing a high level of electrical isolation between the input and output circuits.

Q: Are both DIP6 and SMD6 packages RoHS compliant?
A: Yes, the product is environmentally friendly and compliant with CQC, UL, and VDE requirements, which includes RoHS compliance for halogen-free options.

Q: What is the recommended soldering profile for the SMD6 package?
A: For SMD6, reflow soldering is recommended. The peak temperature should not exceed 260°C, with the time above liquidus (217°C) between 60-150 seconds, limited to three cycles maximum.

About Leon Zhang

Leon Zhang is the founder of LDeepAI, focusing on AI-assisted electronic component sourcing and verified China supply-chain support for overseas buyers. He previously worked within the Huaqiang Group ecosystem, including experience related to HQEW, one of China's well-known electronic component trading platforms. This background gives him practical insight into China's electronic component supply-chain structure, supplier screening, channel verification and cross-border sourcing workflows.

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