UPD75402ACT datasheet(11/48 Pages) NEC

11 / 48 page

µPD75402A(A)

3.5

HANDLING UNUSED PINS

Recommended connection method

Connected to the VSS pin

•

When a pull-up resistor is contained

Connected to the VDD pin

•

When a pull-up resistor is not contained

Connected to the VSS or VDD pin

•

When a pull-up resistor is contained

Input mode

: Connected to the VDD pin

Output mode : Open

•

When a pull-up resistor is not contained

Input mode

: Connected to the VSS or VDD pin

Output mode : Open

Open or directly connected to the VSS pin Note

P00

P01 - P03

P10, P12

P20 - P23

P30 - P33

P50 - P53

P60 - P63

•

Connect a capacitor between the pin and VDD.

Note When the

µPD75402A(A) shares the printed circuit board with the µPD75P402, connect the NC pin

directly to VSS pin.

3.6

NOTES ON USING THE P00 AND RESET PINS

The P00 and RESET pins have the test mode selecting function for testing the internal operation of the

µPD75402A(A) (IC test), besides the functions shown in Sections 3.1 and 3.2.

Applying a voltage exceeding VDD to the P00 and/or RESET pin causes the

µPD75402A(A) to enter the test

mode. When noise exceeding VDD comes in during normal operation, the device is switched to the test mode.

For example, when the wiring from the P00 or RESET pin is too long, noise voltage induced on the wiring

is applied to the pin, driving the voltage at the pin above VDD, which may cause malfunction.

When installing the wiring, lay the wiring in such a way that noise is suppressed as much as possible. If

noise yet arises, use an external part to suppress it as shown below.

•

Connect a diode with low VF (0.3 V or lower)

between the pin and VDD.

VDD

P00, RESET

VDD

P00, RESET

VDD

Diode with

low VF

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