D17133CS datasheet(32/289 Pages) NEC

32 / 289 page

CHAPTER 2

PIN FUNCTIONS

2.3 HANDLING UNUSED PINS

In normal operation mode, it is recommended to process the unused pins as follows:

Table 2-1. Handling Unused Pins

Recommended Measures

Inside Microcontroller

Outside Microcontroller

P0A, P0B, P0C

–

Does not incorporate a pull-up

resistor by the mask option

Incorporates a pull-up resistor

by the mask option.

P0A, P0BP0C

(CMOS port)

Outputs low level without

incorporating pull-up resistor by

the mask option.

Outputs high level with a pull-up

resistor incorporated by the

mask option.

External Interrupt (INT)Note2

–

Directly connected to GND

Does not incorporate a pull-up

resistor by the mask option

Incorporates a pull-up resistor

by the mask option.

Notes

1. When externally pulling up (connecting to VDD through a resistor) or pulling down (connecting to the

GND through a resistor), make sure to pay attention to the port's driving ability and current

consumption. When pulling up or pulling down at a high resistance value, be careful to ensure that

no noise is caused in the relevant pin. Although it depends on the applied circuit as well, it is usual

to choose several tens of k

Ω as the resistance value for pull-up or pull-down.

2. The INT pin is for the test mode setting function as well; connect it directly to the GND when unused.

3. If the applied circuit requires a high level of reliability, be sure to design it so that the RESET signal

is input externally. Also, since the RESET pin is for the test mode setting function as well, connect

it directly to the VDD when unused.

Caution The output levels of the input/output mode and pins are recommended to be fixed by being set

repeatedly in their respective loops in the program.

Remark

The

µPD17P132 and 17P133 do not contain pull-up resistors by the mask option.

Each pin is connected to VDD or

GND through the resistor.Note1

Open

Pin Name

Input mode

P0D, P0E

–

Output mode

Open

P0D and P0E (N-ch

open drain port)

RESETNote3

when using only the built-in

power-ON/power-DOWN reset

Directly connected to VDD

D17133CS Datasheet(PDF) 32 Page - NEC

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