The 32-pin TQFN thermally enhanced package can
dissipate up to 2758.6mW. Calculate power dissipation
in the MAX15048/MAX15049 as a product of the input
voltage and the total REG output current (I
includes quiescent current (I
) and the total gate-drive
comprise the total gate charge of the
low-side and high-side external MOSFETs, f
switching frequency of the converter, and I
escent current of the device at the switching frequency.
Use the following equation to calculate the maximum
power dissipation (P
) in the chip at a given ambient
= 34.5 x (150 - T
PCB Layout Guidelines
Use the following guidelines to lay out the switching volt-
1) Place the IN, REG, and DREG_ bypass capacitors
close to the MAX15048/MAX15049.
2) Minimize the area and length of the high-current
loops from the input capacitor, upper switching
MOSFET, inductor, and output capacitor back to the
input capacitor negative terminal.
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Triple-Output Buck Controllers
3) Keep the current loop formed by the lower switching
MOSFET, inductor, and output capacitor short.
4) Keep SGND and PGND_ isolated and connect them
at one single point close to the negative terminal of
the input filter capacitor.
5) Avoid long traces between the DREG_ bypass
capacitor, low-side driver outputs of the MAX15048/
MAX15049, MOSFET gate, and PGND_. Minimize
the loop formed by the DREG_ bypass capacitor,
bootstrap capacitor, high-side driver output of the
MAX15048/MAX15049, and upper MOSFET gates.
6) Place the bank of the output capacitors close to the
7) Distribute the power components evenly across the
board for proper heat dissipation.
is the qui-
8) Provide sufficient copper area at and around the
switching MOSFETs and inductor to aid in thermal
9) Connect the MAX15048/MAX15049 exposed pad to
a large copper plane to maximize its power dissipa-
tion capability. Connect the exposed pad to SGND.
Do not connect the exposed pad to the SGND pin
directly underneath the IC.
10) Use 2oz copper to keep the trace inductance
and resistance to a minimum. Thin copper PCBs
can compromise efficiency since high currents are
involved in the application. Also, thicker copper
conducts heat more effectively, thereby reducing
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go to www.maxim-ic.com/packages. Note that a “+”, “#”, or
“-” in the package code indicates RoHS status only. Package
drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
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