µPD17P218

11

2.4

PROCESSING OF UNUSED PINS

Process the unused pins as follows:

Table 2-1 Processing of Unused Pins

Pin

Recommended Connection

P0A0-P0A3

Connect to VDD

P0B0-P0B3

Connect to VDD

P0C0-P0C3

Connect to GND

P0D0-P0D3

Connect to GND

P0E0-P0E3

Input

: Connect to VDD or GND

Output : Open

REM

Open

INT

Connect to GND

WDOUT

Connect to GND

2.5

NOTES ON USING INT AND RESET PINS

In addition to the functions shown in 2 PIN FUNCTIONS, the INT and RESET pins also have a function to set a

test mode (for IC testing) in which the internal operations of the

µPD17P218 are tested.

When a voltage higher than VDD is applied to either of these pins, the test mode is set. This means that, even

during normal operation, the

µPD17P218 may be set in the test mode and malfunction if a noise exceeding VDD is

applied.

For example, if the wiring length of the INT or RESET pin is too long, noise superimposed on the wiring line of

the pin may cause the above problem.

Therefore, keep the wiring length of these pins as short as possible to suppress the noise; otherwise, take noise

preventive measures as shown below by using external components.

•

Connect diode with low VF between VDD

and INT/RESET pin

Moreover, if the test mode is set by the INT pin, low level is output from the WDOUT pin. In this case, connect

the WDOUT pin to the RESET pin.

• Connect capacitor between VDD

and INT/RESET pin

V DD

V DD

V DD

V DD

INT, RESET

INT, RESET

Diode with

low V F

5

5