LSP3406
High-efficiency 3A synchronous buck converter with wide input range and adjustable output for industrial applications.
Product Overview
Description
The LSP3406 is a high-efficiency synchronous buck converter capable of delivering up to 3A continuous output current.
With a wide input voltage range of 4.5V to 28V and adjustable output down to 0.8V, this converter is suitable for a variety of industrial and automotive applications.
The device features peak current mode control, internal compensation, and power-good output for easy system design.
Product Series
LSP
Primary Application
Industrial control systems
Key Features
- 3A continuous output current
- Wide 4.5V to 28V input voltage range
- High efficiency up to 95%
- Adjustable switching frequency
- Internal compensation
- Power-good output
- Soft-start function
- Thermal shutdown protection
Specifications
| Input Voltage | 4.5V to 28V |
|---|---|
| Output Voltage | 0.8V to 24V (adjustable) |
| Output Current | 3A continuous |
| Efficiency | Up to 95% |
| Switching Frequency | 300kHz to 2.2MHz (adjustable) |
| Quiescent Current | 25µA (sleep mode) |
| Temperature Range | -40°C to +125°C |
| Package | SOP-8, QFN-16 |
Applications
Industrial control systems
Industrial automation and control
Automotive electronics
Automotive and EV electronics
Battery-powered equipment
Battery and charging management
Distributed power systems
Electronic system design
FPGA and processor power
Electronic system design
FAE Expert Insights
"The LSP3406 is a versatile buck converter that I've used in numerous industrial designs. The wide input range handles everything from 5V logic to 24V industrial supplies. The adjustable frequency allows optimization for efficiency or component size. Internal compensation simplifies design - no need to calculate external components. The efficiency is excellent, often exceeding 93% in typical operating conditions."
Wide input range and high efficiency make it ideal for industrial applications
— David Liu, BeiLuo
Frequently Asked Questions
What is the recommended inductor value for LSP3406?
The recommended inductor value depends on the switching frequency and output current. For 500kHz operation at 3A output, a 4.7µH to 10µH inductor is typical. Higher frequencies allow smaller inductors but may reduce efficiency. The inductor must be rated for at least 1.3 times the maximum output current and have low DC resistance for best efficiency. Shielded inductors are recommended to minimize EMI.
Start with recommended values in datasheet; adjust based on ripple and efficiency requirements.
How do I set the output voltage?
The output voltage is set using a resistor divider from the output to the FB (feedback) pin. The formula is: VOUT = 0.8V × (1 + R1/R2), where R1 is the top resistor and R2 is the bottom resistor to ground. Use 1% tolerance resistors for accurate output voltage. Keep the divider close to the FB pin to minimize noise pickup.
Use standard resistor values; place divider close to FB pin; use 1% tolerance resistors.
What is the thermal performance of LSP3406?
The LSP3406 features excellent thermal performance with thermal shutdown at 160°C and hysteresis of 20°C. The exposed pad package (QFN) provides low thermal resistance to the PCB. Proper PCB layout with thermal vias and copper area is essential for maximum current capability. At 3A output with 24V input and 5V output, the junction temperature rise is approximately 40°C above ambient with good PCB layout.
Use QFN package for best thermal performance; provide adequate copper area and thermal vias.
Can LSP3406 be synchronized to an external clock?
Yes, the LSP3406 can be synchronized to an external clock through the SYNC pin. This allows multiple converters to operate at the same frequency to minimize beat frequencies and reduce EMI. The synchronization range is typically 300kHz to 2.2MHz. When synchronizing, ensure the external clock is stable before enabling the converter.
Use synchronization when operating multiple converters or when specific frequency is required for EMI.
What is the soft-start time and how can it be adjusted?
The LSP3406 includes an adjustable soft-start function to limit inrush current during startup. The default soft-start time is approximately 2ms with the internal capacitor. An external capacitor can be added to the SS pin to increase soft-start time. The formula is: tSS = CSS × 0.8V / 5µA. Longer soft-start times are useful for applications with large output capacitors or strict inrush current limits.
Use longer soft-start for large output caps or strict inrush limits; calculate CSS based on requirements.