The AX9661 from AXTEK is a high-performance, monolithic step-down converter designed for applications requiring compact size, high efficiency, and wide input voltage tolerance. This device integrates a low RDS(ON) power MOSFET and supports continuous output currents up to 600mA, with a wide input range of 4.5V to 55V, making it ideal for distributed power systems, battery chargers, LED drivers, and pre-regulators.

Key Features

• Input Voltage Range: 4.5V to 55V

• Continuous Output Current: 600mA

• Switching Frequency: 2MHz

• Low RDS(ON): 900mΩ internal power MOSFET

• Adjustable Output Voltage: Starting from 0.795V

• Integrated Protections: Overcurrent limit, thermal shutdown, short-circuit protection

• Internal Soft-Start: 0.85ms

• Low Quiescent Current: < 2mA in normal mode, < 4μA in shutdown

• Operating Temperature: –40℃ to +85℃

• Package: Compact SOT23-6

Performance Highlights

• Maintains stable regulation over wide line and load variations

• High efficiency maintained across full load range with PFM mode under light load

• Fast transient response enabled by internal compensation and optional feed-forward capacitor

• Thermal shutdown activates at 160°C with 30°C hysteresis for protection

• Low ripple and fast startup, with excellent output regulation performance

Typical Applications

• Power Meters

• Battery-Powered Devices

• Distributed Power Systems

• WLED Drivers

• Pre-regulators for Linear Regulators

Typical Application Example

• VOUT = 3.3V: R1 = 39kΩ, R2 = 12.5kΩ, L = 6.8–47µH, CIN/COUT = 22µF + 0.1µF ceramic

• VOUT = 12V: R1 = 127.4kΩ, R2 = 9.1kΩ, L = 15–47µH

Protection Features

• Cycle-by-Cycle Overcurrent Protection

• Under-Voltage Lockout (UVLO): Turns off when VIN < 3.5V, starts when VIN > 4.8V

• Thermal Shutdown: Shuts down at 160°C, restarts at 130°C

• Short-Circuit Recovery

Efficiency Performance

The AX9661 delivers over 87% efficiency at 500mA load with VOUT = 12V and input up to 50V. At lighter loads, its PFM operation significantly improves energy efficiency and reduces output ripple.

AX9661 is a cost-effective yet robust choice for compact power designs where space, efficiency, and wide input voltage tolerance are critical. It simplifies the BOM with its internal compensation and protection features, while ensuring stable operation even in demanding conditions.

Contact us for datasheet and sample inquiries.

Email: sales01@axtekic.com

Tel: +86 18922847627