NEC PD78F9488 - Manual (Page 43)

CHAPTER 2 PIN FUNCTIONS
User’s Manual U15331EJ4V1UD
43
2.2.13 RESET
This pin inputs an active-low system reset signal.
2.2.14 X1, X2
These pins are used to connect a crystal resonator for main system clock oscillation.
To supply an external clock, input the clock to X1 and input the inverted signal to X2.
2.2.15 XT1, XT2
These pins are used to connect a crystal resonator for subsystem clock oscillation.
To supply an external clock, input the clock to XT1 and input the inverted signal to XT2.
2.2.16 AV
DD
This is the analog power supply pin of the A/D converter. Always use the same potential as that of the V
DD
pin even
when the A/D converter is not used.
2.2.17 AV
SS
This is the ground potential pin of the A/D converter. Always use the same potential as that of the V
SS
pin even
when the A/D converter is not used.
2.2.18 V
DD
This is the positive power supply pin.
2.2.19 V
SS
This is the ground pin.
2.2.20 V
PP
(flash memory version only)
A high voltage should be applied to this pin when the flash memory programming mode is set and when the
program is written or verified.
Handle the pins in either of the following ways.
• Independently connect a 10 kΩ pull-down resistor.
• Switch this pin to be directly connected to the dedicated flash programmer in programming mode or to V
SS
in
normal operation mode using a jumper on the board.
If the wiring between the V
PP
pin and V
SS
pin is very long or external noise is superimposed on the V
PP
pin, the
user program may not run correctly.