
is1C33L17sPeCifiCations:PreCautionsonMounting
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If conditions (1) to (3) are not satisfied, the OSC3 or PLL output may be jittery and the OSC1 output may
be noisy. When the OSC3 or PLL output is jittery, the operating frequency will be lowered. When the OSC1
output is noisy, operation of the RTC using the OSC1 clock and the CPU core after the system clock is
switched to OSC1 will be unstable.
resetCircuit
The power-on reset signal which is input to the #RESET pin changes depending on conditions (power rise time,
components used, board pattern, etc.). Decide the time constant of the capacitor and resistor after enough tests
have been completed with the application product.
In order to prevent any occurrences of unnecessary resetting caused by noise during operating, components
such as capacitors and resistors should be connected to the #RESET pin in the shortest line.
PowersupplyCircuit
Sudden power supply variation due to noise may cause malfunction. Consider the following points to prevent
this:
(1) The power supply should be connected to the VDD, VDDH, VSS, AVDD, PLVDD and PLVSS pins with patterns
as short and large as possible. In particular, the power supply for AVDD affects A/D conversion precision.
(2) When connecting between the VDD and VSS pins with a bypass capacitor, the pins should be connected as
short as possible.
VDD
VSS
Bypass capacitor connection example
VDD
VSS
a/DConverter
When the A/D converter is not used, the power supply pin AVDD for the analog system should be connected to
VDDH.
arrangementofsignalLines
In order to prevent generation of electromagnetic induction noise caused by mutual inductance, do not arrange a
large current signal line near the circuits that are sensitive to noise such as the oscillation unit and analog input
unit.
When a signal line is parallel with a high-speed line in long distance or intersects a high-speed line, noise may
generated by mutual interference between the signals and it may cause a malfunction. Do not arrange a high-
speed signal line especially near circuits that are sensitive to noise such as the oscillation unit and analog input
unit.
P70 (AIN0)
Large current signal line
High-speed signal line
Large current signal line
High-speed signal line
Prohibited pattern
RTC_CLKO, MCLKO
RTC_CLKI, MCLKI
VSS