UPD17P136ACT datasheet(33/292 Pages) NEC

33 / 292 page

CHAPTER 2 PIN FUNCTIONS

2.3 PROCESSING OF UNUSED PINS

The unused pins should be handled as follows:

Table 2-1. Processing of Unused Pins

Pin Name

Recommended Processing

Internal

External

Port

Input mode

P0A, P0B

Connect pull-up resistor by software

Open

P0C

—

Connect each pin to VDD or GND via

resistorNote 1

P0D, P1A

Pull-up resistor not connected by mask

Directly connect to GND

option

Pull-up resistor connected by mask

Open

option

P1B0Note2

Pull-up resistor not connected by mask

Directly connect to GND

option

Output mode

P0A, P0B, P0C

—

Open

(CMOS port)

P0D, P1A

Outputs low level without pull-up

(N-ch open-

resistor connected by mask option

drain ports)

Outputs high level without pull-up

resistor connected by mask option

External interrupt (INT)

Pull-up resistor not connected by mask

Directly connect to VDD or GND

option

Pull-up resistor connected by mask

Open

option

RESETNote3

Pull-up resistor not connected by mask

Directly connect to VDD

when only internal power-ON/power-

option

down reset function is used

Pull-up resistor connected by mask

option

VADC

—

Directly connect to VDD

Notes 1.

When connecting an external pull-up resistor (to VDD via resistor) or pull-down resistor (to GND via

resistor), make sure that the driving voltage and current consumption of the port are not exceeded. When

connecting a pull-up or pull-down resistor with a high resistance to a port pin, make sure that noise is not

superimposed on the pin. Generally, the resistance of the pull-up or pull-down resistor is about several

Ω, though it varies depending on the application circuit.

Because the P1B0 pin is multiplexed with a test mode setting function, do not connect a pull-up resistor

to this pin using the mask option. Directly connect it to GND.

In an application circuit where high reliability is required, be sure to input the RESET signal from an external

source. Because the RESET pin is multiplexed with a mode setting function, directly connect it to VDD

if not use.

Caution It is recommended that the I/O mode, pull-up of resistors by software, and output levels of pins be

fixed by repeatedly setting in each loop of the program.

Remark

The

µPD17P136A and 17P137A do not have a pull-up resistor as mask option.

UPD17P136ACT Datasheet(PDF) 33 Page - NEC

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