MB91354A 데이터 시트보기 (PDF) - Fujitsu

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MB91354A

32-Bit Proprietary Microcontroller

Fujitsu 

MB91350A Series

■ HANDLING DEVICES

• Preventing Latchup

Latch-up may occur in a CMOS IC if a voltage greater than VCC or less than VSS is applied to an input or output

pin or if an above-rating voltage is applied between VCC and VSS. A latchup,if it occurs, significantly increases

the power supply current and may cause thermal destruction of an element. When you use a CMOS IC, be very

careful not to exceed the maximum rating.

• Treatment of Unused Input Pins

Do not leave an unused input pin open, since it may cause a malfunction. Handle by, for example, using a pull-

up or pull-down resistor.

• About power supply pins

In products with multiple VCC or VSS pins, the pins of the same potential are internally connected in the device

to avoid abnormal operations including latch-up. However, you must connect the pins to an external power supply

and a ground line to lower the electro-magnetic emission level, to prevent abnormal operation of strobe signals

caused by the rise in the ground level, and to conform to the total output current rating.

Moreover, connect the current supply source with the VCC and VSS pins of this device at the low impedance.

It is also advisable to connect a ceramic bypass capacitor of approximately 0.1 µF between VCC and VSS near

this device.

• About Crystal oscillator circuit

Noise near the X0, X1, X0A and X1A pins may cause the device to malfunction. Design the circuit board so that

X0, X1, X0A, X1A, the crystal oscillator (or ceramic oscillator), and the bypass capacitor to ground are located

as close to the device as possible.

It is strongly recommended to design the PC board artwork with the X0, X1, X0A and X1A pins surrounded by

ground plane because stable operation can be expected with such a layout.

• Notes on Using External Clock

When external clock is selected, supply it to X0 pin generally, and simultaneously the opposite phase clock to

X0 must be supplied to X1 pin. However, in this case the stop mode(oscillator stop mode) must not be used.

(This is because the X1 pin stops at High level output in STOP mode.)

Using an external clock (normal)

X0

X1

Note: STOP mode (oscillation stop mode) cannot be used.

• Clock control block

Take the oscillation stabilization wait time during Low level input to the INIT pin.

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