MB39C811 Datasheet, PDF (25/36 Pages) Cypress Semiconductor – Ultra Low Power Buck PMIC Solar/Vibrations Energy Harvesting

MB39C811
11. Layout for Printed Circuit Board
Note the points listed below in layout design
 Place the switching parts^[1] on top layer, and avoid connecting each other through through-holes.
 Make the through-holes connecting the ground plane close to the GND pins of the switching parts^[1]
 Be very careful about the current loop consisting of the input capacitor CVIN, the VIN pin of IC, and the PGND pin.
Place and connect these parts as close as possible to make the current loop small.
 The output capacitor CVOUT and the inductor L are placed adjacent to each other.
 Place the bypass capacitor CVB close to VB pin, and make the through-holes connecting the ground plane close to
the GND pin of the bypass capacitor CVB.
 Draw the feedback wiring pattern from the VOUT pin to the output capacitor CVOUT pin. The wiring connected to
the VOUT pin is very sensitive to noise so that the wiring should keep away from the switching parts^[1]. Especially,
be very careful about the leaked magnetic flux from the inductor L, even the back side of the inductor L.
[1]: Switching parts: IC (MB39C811), Input capacitor (CVIN), Inductor (L), Output capacitor (CVOUT).
Refer to Figure 2.
Figure 16. Example of a Layout Design
feedback wiring pattern
L
VB
C_VB
through-holes
VOUT
VIN
LX
PGND
Top Layer Back Layer
Document Number: 002-08401 Rev *A
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