MB91F345B データシートの表示（PDF） - Fujitsu

部品番号

コンポーネント説明

メーカー

MB91F345B

32-bit Microcontroller

Fujitsu 

MB91345 Series

■ HANDLING DEVICES

• Preventing Latch-up

Latch-up may occur in a COMS IC if a voltage greater than VCC pin, or less than VSS pin is applied to input

and output pins, or if an above-rating voltage is applied between VCC pin and VSS pin. If the latch-up occurs,

the significantly increases the power supply current and may cause thermal destruction of an element. Thus,

When you use a CMOS IC, be very careful not to exceed maximum voltage rating.

• Treatment of Unused input pins

Do not leave an unused input pin open, since it may cause a malfunction. Thus, use pull-up or pull-down resistor.

• About power supply pins

If there are multiple VCC pin or VSS pin, from the point of view of device design, pins to be of the same level

are connected the inside of the device to prevent such malfunctioning as latch-up. Be sure to connect all of them

to the power supply and ground externally for reducing unnecessary radiation, prevent malfunctioning of the

strobe signal due to the rise of ground level, and observe the total output current standard. In addition, consid-

eration should be given to connecting VCC/VSS of this device with as low an impedance as possible from the

current supply source. Also, we recommend connecting a ceramic capacitor of about 0.1 µF as a bypass capacitor

between VCC and VSS near this device.

• About crystal oscillator circuit

Noise near the X0 and X1 pins can cause this device to malfunction. Design the PC board such that X0 and X1

pins, crystal oscillator (or ceramic oscillator) , and bypass capacitor to the ground are placed as near one another

as possible. It is strongly recommended to design the PC board artwork with the X0/X1 pins surrounded by a

ground plane, as it expects stable operations.

Please ask the crystal maker to evaluate the oscillational characteristics of the crystal and this device.

• About mode pins (MD0 to MD2)

These pins should be connected directly to VCC or VSS pins. To prevent the device erroneously switching to

test mode due to noise, design the PC board such that the distance between the mode pins and VCC or VSS

pins is as short as possible and the connection impedance is low.

• About operation at power-on

Be sure to set initialized reset (INIT) with INIT pin immediately after power-on.

Immediately after turning on the power, be sure to continue connecting the Low level input to the INIT pin for

the stabilization wait time required for oscillator circuit, to secure the stabilization wait time of the oscillator and

regulator (For INIT via the INIT pin, the oscillation stabilization wait time setting is initialized to the minimum value) .

• About oscillation input at power on

When turning on the power, be sure that clock input is maintained until the device is released from the oscillation

stabilization wait state.

• Note on power-on/off sequences

When turning on the power, the output pin may be indeterminate until the internal power supply stabilizes.

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