Fujitsu ALL FR 460 Series Application Note page 19

FR460 Hardware Set Up
Chapter 3 Port Input / Unused Pins / Latch-up
The series resistor R reduces the amplitude of the oscillation and decreases the voltage
S
offset at first. The resistor must not be chosen too high, so that the port pin input voltage V is
P
within the positive CMOS/TTL/Automotive level.
© Fujitsu Microelectronics Europe GmbH - 19 - MCU-AN-300033-E-V13