JW1550
High-performance quasi-resonant flyback controller with active burst mode for high efficiency across all loads
Product Overview
Description
The JW1550 is a high-performance quasi-resonant flyback controller designed for high-efficiency offline power supplies up to 65W. It features valley switching operation to minimize switching losses and EMI, with frequency dithering for improved EMI performance.
The controller includes active burst mode that automatically adjusts burst frequency based on load conditions, maintaining high efficiency from heavy load down to no-load conditions. The built-in soft-start and soft-drive functions reduce switching noise and EMI.
Comprehensive protection features include over-voltage protection, over-current protection with leading edge blanking, overload protection, and thermal shutdown. The JW1550 drives an external power MOSFET, allowing flexibility in power level and MOSFET selection. Available in SOP-8 package.
Product Series
JW
Primary Application
High-power adapters
Key Features
- Quasi-resonant valley switching
- Active burst mode for light load efficiency
- Frequency dithering for EMI reduction
- Built-in soft-start function
- Soft-drive for reduced EMI
- Comprehensive protection features
- External MOSFET drive for flexibility
- Low startup current
Specifications
| Input Voltage Range | 85VAC - 265VAC |
|---|---|
| Output Power | Up to 65W |
| MOSFET Drive | External |
| Efficiency | Up to 90% |
| Maximum Frequency | 100kHz |
| Standby Power | <100mW |
| Operating Temperature | -40°C to +85°C |
| Package | SOP-8 |
Applications
High-power adapters
Electronic system design
LCD TV power supplies
Electronic system design
Desktop computer power supplies
Electronic system design
Industrial power supplies
Industrial automation and control
LED drivers
Motor drive and control systems
FAE Expert Insights
"The JW1550 is my go-to controller for medium-power offline supplies requiring high efficiency. The quasi-resonant valley switching provides measurable efficiency improvements, especially at high-line input. I've used this controller in designs up to 65W with excellent results. The active burst mode is particularly impressive - it maintains efficiency above 80% even at 10% load, which is critical for meeting modern efficiency standards. The frequency dithering feature really helps with EMI compliance - I've seen 3-6dB improvement in conducted emissions. One design tip: the valley detection requires careful transformer design and PCB layout. Keep the drain sense trace short and away from noisy nodes. The soft-drive feature reduces EMI but slightly increases switching losses - you may want to adjust the gate resistor for your specific application. Overall, an excellent controller for high-efficiency offline supplies."
High-performance quasi-resonant controller with active burst mode for excellent light-load efficiency
— Robert Zhang, BeiLuo
Frequently Asked Questions
What is the maximum power of JW1550?
The JW1550 can control flyback converters up to 65W output power. The actual maximum depends on the external MOSFET selection, transformer design, and thermal management. With a suitable MOSFET and proper heatsinking, 65W is achievable at universal input voltage.
Up to 65W with proper MOSFET and thermal design; external MOSFET allows flexibility.
How does active burst mode work?
Active burst mode automatically adjusts the burst frequency based on load conditions. At light loads, the controller enters burst mode, switching only when output voltage drops below a threshold. The burst frequency decreases as load decreases, minimizing switching losses while maintaining regulation.
Active burst mode maintains high efficiency at light loads; automatically adapts to load conditions.
What external MOSFET should I use with JW1550?
Select a MOSFET with voltage rating at least 600V for universal input applications. Current rating depends on output power - typically 4-6A for 30-65W applications. Consider Rds(on), gate charge, and thermal characteristics. Popular choices include Infineon IPA60R600E6 or equivalent.
600V+ rating; 4-6A current for 30-65W; consider Rds(on) and gate charge.
What is frequency dithering and why is it used?
Frequency dithering modulates the switching frequency over a small range, spreading EMI energy across a wider frequency band. This reduces peak EMI emissions, making it easier to meet EMC regulations. The JW1550 includes built-in frequency dithering to improve EMI performance.
Frequency dithering reduces peak EMI; helps meet EMC regulations without additional filtering.
How do I design the valley detection circuit?
The valley detection circuit senses the transformer drain voltage through a resistor divider. Connect a resistor from drain to VS pin, and another from VS pin to ground. The ratio should be selected to ensure proper valley detection across input voltage range. Follow the application note for specific values.
Use resistor divider from drain to VS pin; follow application note for specific values.
What is the difference between JW1550 and JW1763B?
JW1550 is a controller that drives an external MOSFET, suitable for higher power applications up to 65W. JW1763B has an integrated 650V MOSFET, suitable for lower power applications up to 24W. JW1550 offers more flexibility in MOSFET selection and higher power capability.
JW1550 for 30-65W with external MOSFET; JW1763B for 10-24W with integrated MOSFET.
What startup circuit is recommended for JW1550?
JW1550 features low startup current, allowing direct startup from rectified AC line through a startup resistor. Use a high-voltage resistor (typically 2-5MΩ) from rectified DC bus to VCC. Once operating, the auxiliary winding supplies VCC. Size the startup resistor for acceptable startup time while minimizing standby power.
Use 2-5MΩ startup resistor from DC bus; auxiliary winding supplies VCC during operation.