The LM5146-Q1 100-V synchronous buck controller regulates from a high input voltage source or from an input rail subject to high voltage transients, minimizing the need for external surge suppression components. A high-side switch minimum on-time of 40 ns gives large step-down ratios, enabling the direct step-down conversion from a 48-V nominal input to low-voltage rails for reduced system complexity and solution cost. The LM5146-Q1 continues to operate during input voltage dips as low as 5.5 V, at nearly 100% duty cycle if needed, making it an excellent choice for high-performance 48-V battery automotive applications, ADAS (surround view ECU) and HEV/EV systems.
Forced-PWM (FPWM) operation eliminates switching frequency variation to minimize EMI, while user-selectable diode emulation lowers current consumption at light-load conditions. Measuring the voltage drop across the low-side MOSFET or with an optional current sense resistor gives cycle-by-cycle overcurrent protection. The adjustable switching frequency as high as 1 MHz can be synchronized to an external clock source to eliminate beat frequencies in noise-sensitive applications.
The LM5146-Q1 voltage-mode controller with line feedforward drives external high-side and low-side N-channel power switches with robust 7.5-V gate drivers suitable for standard-threshold MOSFETs. Adaptively-timed gate drivers with 2.3-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 input voltage and high frequency. The LM5146-Q1 can be powered from the output of the switching regulator or another available source, further improving efficiency.
A 180° out-of-phase clock output relative to the internal oscillator at SYNCOUT works well for cascaded or multi-channel power supplies to reduce input capacitor ripple current and EMI filter size. Additional features of the LM5146-Q1 include a configurable soft start, an open-drain power-good monitor for fault reporting and output monitoring, monotonic start-up into prebiased loads, integrated VCC bias supply regulator and bootstrap diode, external power supply tracking, precision enable input with hysteresis for adjustable line undervoltage lockout (UVLO), hiccup-mode overload protection, and thermal shutdown protection with automatic recovery.
The LM5146-Q1 controller is offered in a 4.5-mm × 3.5-mm thermally enhanced, 20-pin VQFN package with additional spacing for high-voltage pins and wettable flanks for optical inspection of solder joint fillets.