MP2120 – 2.5A, 5.5V SYNCHRONOUS STEP-DOWN CONVERTER
External Schottky Diode
For this part, an external schottky diode is
recommended to be placed close to "SW" and
"GND" pins, especially when the output current is
larger than 2A.
With the external schottky diode, the voltage
spike and negative kick on "SW" pin can be
minimized; moreover, the conversion efficiency
can also be improved a little.
For the external schottky diode selection, it's
noteworthy that the maximum reverse voltage
rating of the external diode should be larger than
the maximum input voltage. As for the current
rating of this diode, 0.5A rating should be
sufficient.
PCB Layout Guide
Top Layer
PCB layout is very important to achieve stable
operation. It is highly recommended to duplicate
EVB layout for optimum performance. If change
is necessary, please follow these guidelines as
follows. Here, the typical application circuit is
taken as an example to illustrate the key layout
rules should be followed.
1) For MP2120, a PCB layout with more than (or)
four layers is recommended.
2) The high current paths (GND, IN and SW)
should be placed very close to the device with
short, direct and wide traces.
3) For MP2120, two input ceramic capacitors (2 x
(10μF~22μF)) are strongly recommended to be
placed on both sides of the MP2120 package
and keep them as close as possible to the “IN”
and “GND” pins. If this placement is not possible,
a ceramic cap (10μF~47μF) must be placed
across PIN7-“IN”and PIN9-“GND” since the
internal V
CC
supply is powered from PIN7, and
good decoupling is needed to avoid any
interference issues.
4) The external feedback resistors shall be
placed next to the FB pin. Keep the FB trace as
short as possible. Don’t place test points on FB
trace if possible.
5) Keep the switching node SW short and away
from the feedback network.
Inner Layer1
Inner Layer2
MP2120 Rev. 0.92
9/7/2011
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