
CHAPTER 2 PIN FUNCTIONS
Preliminary User’s Manual U16228EJ1V0UD
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2.2.14 RESET
This is the active-low system reset input pin.
2.2.15 REGC
This is the pin for connecting the capacitor for the regulator. Connect this pin to VSS via a 0.1
F capacitor. To use
the CPU at high speed (fXP = 10 MHz, VDD = 4.0 to 5.5 V), connect this pin directly to VDD and apply the same voltage
to it as the VDD pin.
2.2.16 X1 and X2
These are the pins for connecting a crystal resonator for X1 input clock oscillation.
When supplying an external clock, input a signal to the X1 pin and input the inverse signal to the X2 pin.
2.2.17 XT1 and XT2
These are the pins for connecting a crystal resonator for subsystem clock oscillation.
When supplying an external clock, input a signal to the XT1 pin and input the inverse signal to the XT2 pin.
2.2.18 VDD and EVDD
VDD is the positive power supply pin for other than ports.
EVDD is the positive power supply pin for ports.
2.2.19 VSS and EVSS
VSS is the ground potential pin for other than ports.
EVSS is the ground potential pin for ports.
2.2.20 VPP (flash memory versions only)
This is a pin for flash memory programming mode setting and high-voltage application for program write/verify.
Connect directly to EVSS or VSS in the normal operation mode.
2.2.21 IC (mask ROM versions only)
The IC (Internally Connected) pin is provided to set the test mode to check the 78K0/KE1 Series at shipment.
Connect it directly to EVSS or VSS pin with the shortest possible wire in the normal operation mode.
When a potential difference is produced between the IC pin and the EVSS or VSS pin because the wiring between
these two pins is too long or external noise is input to the IC pin, the user’s program may not operate normally.
Connect the IC pin directly to EVSS or VSS.
As short as possible
IC
EVSS or VSS