BP3288
High-efficiency quasi-resonant flyback controller with valley switching for adapter applications up to 65W
Product Overview
Description
The BP3288 is a high-performance quasi-resonant (QR) flyback PWM controller designed for high-efficiency power adapter and power supply applications. It features valley switching for reduced switching losses and improved EMI performance.
This controller automatically detects the drain voltage valley and turns on the MOSFET at the optimal point to minimize switching losses. The frequency foldback function maintains high efficiency across the entire load range.
Built-in protection features include over-voltage protection, over-load protection, short-circuit protection, and over-temperature protection. The BP3288 achieves excellent light-load efficiency and low standby power.
Product Series
BP
Primary Application
High-power adapters
Key Features
- Quasi-resonant valley switching
- Frequency foldback for light-load efficiency
- Low standby power consumption
- Built-in soft start
- Comprehensive protection features
- Small SOT23-6 package
Specifications
| Input Voltage | 85V-265V AC |
|---|---|
| Output Power | Up to 65W |
| Switching Frequency | Variable (QR mode) |
| Standby Power | <50mW |
| Efficiency | >90% at full load |
| MOSFET Drive | External |
| Package | SOT23-6 |
Applications
High-power adapters
Electronic system design
Notebook adapters
Electronic system design
Industrial power supplies
Industrial automation and control
Gaming console power
Electronic system design
High-power chargers
Battery and charging management
FAE Expert Insights
"The BP3288 is an excellent QR controller for medium to high-power adapter applications. The valley switching provides measurable efficiency improvements compared to traditional PWM controllers, especially at light loads. In my experience designing 45-65W adapters, this controller consistently achieves 90%+ efficiency at full load and maintains good efficiency down to 25% load. The frequency foldback function is well-implemented, providing smooth transitions between QR and burst modes. I particularly like the small SOT23-6 package which saves PCB space. The external MOSFET drive allows flexibility in selecting the optimal power switch for your application. For high-density adapters, pair this with a good synchronous rectifier controller."
High-efficiency QR controller with excellent light-load performance
— James Zhang, BeiLuo
Frequently Asked Questions
How does valley switching improve efficiency?
Valley switching turns on the MOSFET when the drain voltage reaches its minimum point in the resonant ringing, reducing switching losses. In hard-switching converters, turn-on occurs at high voltage causing significant switching losses (0.5 × Coss × V² × f). Valley switching minimizes this by switching at low voltage. The efficiency improvement is most noticeable at high input voltages and light loads where switching losses dominate. Typical efficiency improvements of 2-5% can be achieved compared to hard-switching at light loads.
Use QR controllers for applications requiring high efficiency across wide load ranges. Contact LiTong for QR design optimization.
What is frequency foldback and how does it work?
Frequency foldback reduces switching frequency as load decreases to maintain high efficiency. At light loads, switching losses become dominant over conduction losses. By reducing switching frequency, the controller minimizes switching losses while maintaining output regulation. The BP3288 smoothly transitions from QR mode at high loads to burst mode at very light loads. This ensures excellent efficiency across the entire operating range, achieving <50mW standby power and good light-load efficiency required by modern energy standards.
Frequency foldback is automatic. Contact LiTong for light-load efficiency optimization.
How do I select the external MOSFET for BP3288?
External MOSFET selection criteria: 1) Voltage rating - select 600V or 650V for universal input (85V-265V AC) applications, 2) Current rating - choose Rds(on) based on thermal constraints and efficiency targets, 3) Gate charge - lower Qg reduces driver losses, 4) Output capacitance (Coss) - affects valley switching timing, 5) Package - TO-220, TO-220F, or D2PAK based on thermal requirements. Super junction MOSFETs offer lower Rds(on) × Qg products for better performance. BPSemi can recommend suitable MOSFETs for your application.
Contact LiTong for MOSFET selection guidance based on your power and efficiency requirements.
What are the key layout considerations for QR converters?
QR converter layout priorities: 1) Minimize the switching loop area (input cap → MOSFET → transformer primary → input cap), 2) Keep the current sense resistor close to the controller with Kelvin connection, 3) Separate power ground and signal ground, connecting at a single point, 4) Place VCC decoupling capacitor close to the IC, 5) Keep the drain node away from sensitive feedback traces, 6) Provide adequate copper area for the MOSFET drain tab for heat dissipation. Good layout is critical for both EMI performance and reliable operation.
Follow BPSemi layout guidelines or contact LiTong for PCB layout review services.
Can BP3288 be used for power factor correction (PFC) applications?
The BP3288 is designed for DC/DC conversion with quasi-resonant operation and is not suitable for active PFC applications. For PFC applications, use dedicated PFC controllers like BPSemi's BP series PFC controllers. However, the BP3288 can be used in two-stage designs where a separate PFC stage provides power factor correction and the BP3288 controls the DC/DC output stage. This approach is common in higher power applications (>75W) where PFC is required.
For PFC applications, use dedicated PFC controllers. Contact LiTong for two-stage PFC+DC/DC design guidance.