R-IN32M4-CL3 User's Manual: Board design edition
4. PLL Power Supply Pins
R18UZ0074EJ0100
Page 11 of 61
Dec 24, 2019
4.2
Notes on Placement of Peripheral Components
The 0.1-
F ceramic capacitor (C1) should be placed immediately close to R-IN32M4-CL3 (in the immediate vicinity of
the pin).
Figure 4.2 is a schematic view from below the board.
In addition, the wiring patterns for the electrolytic capacitor (C2) and ferrite beads running parallel to other signal lines
should be avoided.
PLL_
GND
PLL_
VDD
C1
Pay particular attention to the effects of
noise from signals with wiring running
parallel to these lines in this region.
C2
FB
GND
FB
Power supply
Figure 4.2 Schematic View from Below the Board
Caution:
PLL_VDD and PLL_GND lines should be as short and thick as possible in PCB wiring.
Longer wiring leads to stronger crosstalk because the LC components of the wiring increase,
more readily leading to effects.