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CHAPTER 2
PIN FUNCTIONS
User’s Manual U12790EJ2V0UD
2.2.15 X1, X2
These are crystal resonator connection pins for system clock oscillation.
2.2.16 REGOSC
This is the oscillator regulator pin. Connect to GND via a 0.1
F capacitor.
2.2.17 REGCPU
This is the CPU power supply regulator pin. Connect to GND via a 0.1
F capacitor.
2.2.18 VDD
This is the positive power supply pin.
2.2.19 GND0 to GND2
These are ground potential pins.
2.2.20 VDDPORT
This is the positive power supply pin for ports.
2.2.21 GNDPORT
This is the ground potential pin for ports.
2.2.22 VDDPLL
This is the positive power supply pin for the PLL.
2.2.23 GNDPLL
This is the ground potential pin for the PLL.
2.2.24 AVDD
This is the analog power supply pin of the A/D converter.
Always keep the voltage on this pin at the same level as that on the VDD pin even when the A/D converter is not
used.
2.2.25 AVSS
This is the ground pin of the A/D converter.
Always keep the voltage on this pin at the same level as that on the GND0, GND1, or GND2 pin even when the
A/D converter is not used.
2.2.26 VPP (
PD178F098 only)
This pin applies a high voltage when the flash memory programming mode is set or when a program is written
or verified.
Connect this pin in either of the following ways.
Connect independently to a 10 k
 pull-down resistor.
By using a jumper on the board, connect directly to the dedicated flash programmer in the programming mode
or to GND in the normal operation mode.
When the wiring between the VPP pin and GND pin is long or external noise is input to the VPP pin, the user’s program
may not run normally.