UPD75004 データシートの表示（PDF） - NEC => Renesas Technology

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UPD75004

4-BIT SINGLE-CHIP MICROCOMPUTER

NEC => Renesas Technology 

µPD75004, 75006, 75008

3.6 NOTES ON USING THE P00/INT4, AND RESET PINS

5

In addition to the functions described in Sections 3.1 PORT PINS and 3.2 NON PORT PINS, an exclusive

function for setting the test mode, in which the internal fuctions of the µPD75008 are tested (solely used for

IC tests), is provided to the P00/INT4 and RESET pins.

If a voltage exceeding VDD is applied to either of these pins, the µPD75008 is put into test mode. Therefore,

even when the µPD75008 is in normal operation, if noise exceeding the VDD is input into any of these pins, the

µPD75008 will enter the test mode, and this will cause problems for normal operation.

As an example, if the wiring to the P00/INT4 pin or the RESET pin is long, stray noise may be picked up

and the above montioned problem may occur.

Therefore, all wiring to these pins must be made short enough to not pick up stray noise. If noise cannot

be avoided, suppress the noise using a capacitor or diode as shown in the figure below.

• Connect a diode having a low VF across

P00/INT4 and RESET, and VDD. (0.3 V max.)

VDD

• Connect a capacitor across P00/INT4 and

RESET, and VDD.

VDD

Low VF

diode

VDD

P00/INT4, RESET

VDD

P00/INT4, RESET

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