A high power density, high-efficiency regulator solution uses automotive grade 100-V power MOSFETs in SON 5-mm × 6-mm packages, together with a low-DCR inductor and all-ceramic capacitor design. The design occupies a footprint of 30 mm × 15 mm on a single-sided PCB. The overcurrent (OC) setpoint in this design is set at 12 A based on the resistor R_ILIM and the 10-mΩ R_DS(on) of the low-side MOSFET (typical at T_J = 25°C and V_GS = 10 V). The 12-V output is connected to VCC through a diode, D1, to reduce IC bias power dissipation at high input voltages.

The selected buck converter powertrain components are cited in Table 9-8, including power MOSFETs, buck inductor, input and output capacitors, and ICs. Using the LM5145-Q1 Quickstart Calculator, compensation components are selected based on a target loop crossover frequency of 40 kHz and phase margin greater than 55°. The output voltage soft-start time is 6 ms based on the selected soft-start capacitance, C_SS, of 47 nF.

As shown in Figure 9-16, a 2.2-Ω resistor in series with C_BST is used to slow the turn-on transition of the high-side MOSFET, reducing the spike amplitude and ringing of the SW node voltage and minimizing the possibility of Cdv/dt-induced shoot-through of the low-side MOSFET. If needed, place an RC snubber (for example, 2.2 Ω and 100 pF) close to the drain (SW node) and source (PGND) terminals of the low-side MOSFET to further attenuate any SW node voltage overshoot and/or ringing. Please refer to the application note Reduce Buck Converter EMI and Voltage Stress by Minimizing Inductive Parasitics for more detail.