DFE252012F-R47M datasheet(114/122 Pages) AD

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must be high enough to absorb the inductor energy while transitioning from full-load to no-load conditions. When

using high-capacitance, low-ESR capacitors, the filter capacitor’s ESR dominates the output-voltage ripple in continuous

conduction mode. Therefore, the size of the output capacitor depends on the maximum ESR required to meet the output-

voltage ripple specifications.

General PCB Layout Guidelines

● The power components should be placed first followed by the small analog control signals (see Figure 15).

● It is important to always have a ground layer next to the power stage layer because a solid ground layer provides

an uninterrupted ground return path between the input and the output capacitors during switch on-time (a solid plane

minimizes inductance to the absolute minimum and is also a very good thermal conductor that can act as a heat sink).

● Thick copper is recommended for the external high current power layers to minimize the PCB conduction loss and

thermal impedance.

● The power stage loop that is made by the input capacitor (CIN), the LX trace, the inductor (L), and the output capacitor

(COUT) coming back to the PGNDx pins should be minimized in consideration of EMC.

● The input capacitors (CIN) should be located close to the input pins of each phase.

● Bypass capacitors for the VDD, the VL12, the VL34, and the BSTx pins should be placed as close as possible.

● Analog ground (AGND) and power ground (PGND) pins should be directly connected to the ground plane separately

to avoid common impedance ground.

● It is recommended to avoid a direct connection of the SYS and its AGND traces to the nearest IN and the PGND

traces

● The output-voltage sensing trace should not intersect the power stage (the loop made by the LX trace, inductor, output

capacitor and the PGND).

● It is important to have impedance matching between phases for stable operation in multiphase configuration (the

output PCB trace of each phase should be as symmetric as possible).

● For multiphase configurations, the output-voltage sensing pins for the master phase should be connected to the

middle point of the output phases.

MAX77542

16VIN/16A, Quad-Phase High-Efficiency Buck

Converter

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