Recommendation for Hardware Setup 32-Bit FR81S Family
Document No. 002-09375 Rev. *B
12
3.6
Recommended Power Supply Circuit
To meet EMC requirements for the target board, a noiseless supply is necessary. Therefore, the supply should be
filtered as shown in Figure 10. Switched IO pins like stepper motor controller or external bus interface can generate
spikes on the supplies. These are difficult to filter using capacitors only. A series inductor (ferrite, e.g. WE742792022)
is therefore recommended, as shown.
Figure 10. Principal Supply circuit
L
10uF
GND
MCU
AVcc
Vcc
VSS
GND
AVSS
5V
10uF
GND
GND
100nF
X7R
Vcc
L
10uF
GND
5V
10uF
GND
Close to
MCU pins
AVRH
R
2
*
*R2 (e.g. 10R) : Optional
GND
GND
100nF
X7R
GND
C*
C*
GND
100nF
X7R
GND
GND
100nF
X7R
GND
C*
C*
*C (e.g. 1nF) : Optional
