WL2801
2A synchronous step-down DC-DC converter with 2.5V-5.5V input, adjustable output, and 3MHz switching frequency for co...
Product Overview
Description
The WL2801 is a high-efficiency 2A synchronous buck converter designed for portable and battery-powered applications.
With a wide input voltage range of 2.5V to 5.5V and adjustable output from 0.6V to VIN, it can power a variety of loads from single-cell Li-ion batteries or 5V rails.
The 3MHz switching frequency allows the use of small inductors and capacitors, minimizing PCB area and solution cost.
Product Series
WL
Primary Application
Smartphone power management
Key Features
- High efficiency: up to 95% at 3.3V to 1.8V conversion
- 3MHz switching frequency for compact solution
- Synchronous rectification for high efficiency
- 100% duty cycle for low dropout operation
- Internal soft-start and compensation
- Current limit and thermal shutdown protection
Specifications
| Input Voltage | 2.5V to 5.5V |
|---|---|
| Output Voltage | 0.6V to VIN (adj) |
| Output Current | 2A continuous |
| Switching Frequency | 3MHz |
| Efficiency | Up to 95% |
| Quiescent Current | 40uA |
| Package | SOT-23-5, DFN-6 |
Applications
Smartphone power management
Electronic system design
Tablet and e-reader
Electronic system design
Portable media players
Electronic system design
Battery-powered equipment
Battery and charging management
IoT devices
Electronic system design
FAE Expert Insights
"The WL2801 is an excellent choice for battery-powered applications requiring high efficiency. The 3MHz switching frequency is higher than many competitors, allowing smaller external components. I've achieved solution sizes under 25mm² including inductor and capacitors. The efficiency peaks at 95% for typical 3.3V to 1.8V conversion, which is impressive for this current range. The 40uA quiescent current helps extend battery life in standby. The internal compensation simplifies design - no need to calculate external compensation networks. For compact, efficient power conversion, this buck converter delivers excellent performance."
Compact high-efficiency solution with 3MHz operation
— Robert Lee, BeiLuo
Frequently Asked Questions
What inductor value is recommended for WL2801?
The WL2801 operates at 3MHz switching frequency, allowing small inductor values. For most applications, a 1.0uH inductor is recommended. This provides good balance between ripple current, transient response, and physical size. The inductor should have saturation current rating at least 20% higher than maximum load current (2.4A minimum for 2A load). Recommended inductors include 2.0mm x 1.6mm chip inductors for compact designs or 3.0mm x 3.0mm inductors for lowest DCR and highest efficiency. Inductor selection affects output ripple, transient response, and overall efficiency.
Use 1.0uH inductor with >2.4A saturation current. Contact us for recommended inductor part numbers.
What is the efficiency of WL2801 at light loads?
The WL2801 maintains good efficiency across the load range. At heavy loads (1-2A), efficiency is 90-95% depending on input/output voltages. At medium loads (100-500mA), efficiency is typically 85-92%. At light loads (10-50mA), the converter automatically enters PFM (Pulse Frequency Modulation) mode to maintain efficiency above 70%. The 40uA quiescent current helps maintain efficiency at very light loads. For battery-powered applications, this efficiency profile maximizes battery life across various usage patterns.
For battery applications, efficiency at your typical load current is most important. Contact us for efficiency curves at your operating points.
What output capacitor is recommended for WL2801?
The WL2801 requires output capacitance of at least 10uF for stable operation. Ceramic capacitors with X5R or X7R dielectric are recommended for best performance. The capacitor should be rated for at least 10V and placed close to the IC pins. For applications with large load transients, additional capacitance (22-47uF) may be beneficial. Low ESR ceramic capacitors provide lowest output ripple. The output capacitor affects loop stability, transient response, and output ripple voltage. Avoid tantalum or electrolytic capacitors as primary output capacitance due to higher ESR.
Use 10uF X5R/X7R ceramic capacitor minimum. Add more capacitance for large load transients. Contact us for capacitor recommendations.
Does WL2801 support 100% duty cycle operation?
Yes, the WL2801 supports 100% duty cycle operation, which means the high-side switch can remain on continuously. This allows the output voltage to approach the input voltage minus the RDS(on) drop of the high-side MOSFET. At 100% duty cycle, the converter operates in dropout mode similar to an LDO. This feature is important for battery-powered applications where the battery voltage drops close to the required output voltage. The transition to 100% duty cycle is automatic and seamless.
100% duty cycle maximizes battery life by extracting all available energy. Contact us for dropout voltage characteristics.
What is the switching frequency of WL2801 and can it be adjusted?
The WL2801 operates at a fixed 3MHz switching frequency. This frequency is internally set and cannot be adjusted externally. The 3MHz frequency was selected as an optimal balance between solution size, efficiency, and EMI. Higher frequencies allow smaller components but reduce efficiency. Lower frequencies improve efficiency but require larger inductors and capacitors. The fixed frequency simplifies design - no external frequency setting components are needed. The frequency remains constant across load and voltage conditions, making EMI filtering predictable.
The fixed 3MHz frequency is suitable for most applications. Contact us if your application requires different switching frequency.