Table of Contents
Advertisement
RX Family
2. Board Design
2.1 Power Supply Pins
Connect the power supply pins to GND via a bypass capacitor (decoupling capacitor). Use a capacitor with
good frequency characteristics, such as a ceramic capacitor. The wiring length between each power supply
pin and the bypass capacitor must be equal and as short as possible. In addition, pair the appropriate power
supply pins. For example, the VCC pin, AVCC pin, and VREFH pin should be paired with the VSS pin, AVSS
pin, and VREFL pin, respectively. Refer to the User's Manual: Hardware of the product used for more details
on pairing pins. The traces for the power supply pins must be wider than traces for other signal lines and
must be connected to the power supply and GND via a bypass capacitor. Figure 2.1 shows example
connections of power supply pins and bypass capacitors.
Bad power supply wiring pattern
Not appropriate because the power
supply pins are connected to GND
without an intervening capacitor.
RX Family
VSS
VCC
Digital power
supply
C
Capacitor
Wiring trace
Through hole
Figure 2.1 Example Connections of Power Supply Pins and Bypass Capacitors
Refer to the application notes below for details of the analog power-supply pins. The latest versions and
guides to new products can be downloaded from the Renesas Electronics website.
• RX610 Group: Notes on Analog Power Supply Printed Circuit Board Patterns (R01AN0271EJ)
• RX62N Group, RX621 Group: Notes on Analog Power Supply Printed Circuit Board Patterns
(R01AN0269EJ)
• RX62T Group: Notes on Analog Power Supply Printed Circuit Board Patterns (R01AN0638EJ)
Board design hint
A bypass capacitor connected to the power supply pins can be placed so as to route noise to GND
during MCU operation.
R01AN1411EJ0110 Rev.1.10
Oct.26.21
RX Family
Digital GND
C
Good power supply wiring pattern
Appropriate because the power
supply pins are connected to GND
via a capacitor.
Digital GND
VSS
VCC
Digital power
supply
Connections between pins, capacitor, and
through hole are as short as possible.
Hardware Design Guide
C
Page 7 of 32
Advertisement
Table of Contents
