Xt1, Xt2; Vdd; Vss; Vpp ( Μ Pd78F9436, 78F9456 Only) - NEC UPD789426 Series User Manual

2.2.17 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.
2.2.18 V
DD
This is the positive power supply pin.
2.2.19 V
SS
This is the ground pin.
µ
2.2.20 V ( PD78F9436, 78F9456 only)
PP
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.
Connect this pin in either of the following ways.
• Independently connect to a 10 kΩ pull-down resistor.
• By using a jumper on the board, connect directly to the dedicated flash programmer in the programming mode or
to V in the normal operation mode.
SS

2.2.21 IC (mask ROM version only)

The IC (Internally Connected) pin is used to set the
test mode before shipment. In the normal operation mode, directly connect this pin to the V
wiring length as possible.
If a potential difference is generated between the IC pin and V
noise superimposed on the IC pin, the user program may not run correctly.
CHAPTER 2 PIN FUNCTIONS
µ
PD789426, 789436, 789446, and 789456 Subseries in the
• Directly connect the IC pin to the V
V IC
SS
User's Manual U15075EJ2V1UD
pin due to a long wiring length, or an external
SS
pin.
SS
Keep short
pin with as short a
SS
43