The LM514575-V synchronous buckcontroller is designed to regulate from a high input voltage source or from an input rail subjectto high voltage transients, minimizing the need for external surge suppression components. Ahigh-side switch minimum on-time of 40 ns facilitates large step-down ratios, enabling the directstep-down conversion from a 48 V nominal input to low-voltage rails for reduced system complexity and solution cost. TheLM5145RGYR continues tooperate during input voltage dips as low as 6 V, at nearly 100% duty cycle if needed, making itwell suited for high-performance industrial control, robotic, datacom, and RF power amplifierapplications.

Forced-PWM (FPWM) operation eliminates frequency variation to minimize EMI, while auser-selectable diode emulation feature lowers current consumption at light-load conditions.Cycle-by-cycle overcurrent protection is accomplished by measuring the voltage drop across thelow-side MOSFET or by using an optional current sense resistor. The adjustable switching frequencyas high as 1 MHz can be synchronized to an external clock source to eliminate beat frequencies innoise-sensitive applications.

The LM5145voltage-mode controller drives external high-side and low-side N-channel power switches with robust7.5-V gate drivers suitable for standard-threshold MOSFETs. Adaptively-timed gate drivers with2.3-A source and 3.5-A sink capability minimize body diode conduction during switching transitions,reducing switching losses and improving thermal performance when driving MOSFETs at high inputvoltage and high frequency. The LM5145RGYR can be powered from the output of the switching regulator oranother available source, further improving efficiency.

A 180° out-of-phase clock output relative to the internal oscillator at SYNCOUT is idealfor cascaded or multi-channel power supplies to reduce input capacitor ripple current and EMIfilter size. Additional features of the LM5145RGYR include a configurable soft-start, an open-drain Power Good monitorfor fault reporting and output monitoring, monotonic start-up into prebiased loads, integrated VCCbias supply regulator and bootstrap diode, external power supply tracking, precision enable inputwith hysteresis for adjustable line undervoltage lockout (UVLO), hiccup-mode overload protection,and thermal shutdown protection with automatic recovery.

The LM5145controller is offered in a 3.5-mm × 4.5-mm thermally-enhanced, 20-pin VQFN package with additionalspacing for high-voltage pins and wettable flanks for optical inspection of solder jointfillets.

Feature

(Picture: Diagram)