The LMR544xx converter is an easy-to-use synchronous step-down DC-DC converter operating from a 4-V to 36-V supply voltage. The LMR54410 is capable of delivering up to 1-A DC load current in a very small design size while the LMR54406 is capable of delivering up to 0.6-A load current. The family has multiple versions applicable to various applications. See Section 4 for detailed information.

The LMR544xx employs fixed-frequency peak-current mode control. The PFM version enters PFM mode at light load to achieve high efficiency. A FPWM version is provided to achieve low output voltage ripple, tight output voltage regulation, and constant switching frequency at light load. The device is internally compensated, which reduces design time and requires few external components.

Additional features, such as precision enable and internal soft start, provide a flexible and easy-to-use design for a wide range of applications. Protection features include the following:

• Thermal shutdown
• V_IN undervoltage lockout
• Cycle-by-cycle current limit
• Hiccup mode short-circuit protection

This family of devices requires very few external components and has a pinout designed for simple, optimal PCB layout.