MB91133 データシートの表示（PDF） - Fujitsu

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MB91133

32-Bit RISC Microcontroller

Fujitsu 

MB91133/MB91F133

s HANDLING DEVICES

1. Points to Note on Handling Devices

(1) Latch-up prevention

Latch-up may occur by CMOS IC if a voltage in excess of VCC5 or lower than VSS is applied to the input/output

pins, or if the voltage exceeds the rating between VCC5 and VSS. If latch-up occurs, the electrical current increases

significantly and may destroy certain components due to excessive heat, so great care must be taken to ensure

that the maximum rating is not exceeded during use.

(2) Handling Pins

• Handling unused pins

Input pins that are not used should be pulled up or down as they may cause erroneous operations if left open.

• Handling N.C. pins

N.C. pins must be opened for use.

• Handling output pins

Excessive electric current may flow if the output pin is shorted by the power source or other output pins, or

connected to large loads. If such status is prolonged, the device is liable to be damaged, so great care must

be taken to ensure that the usage volume does not exceed the maximum rating.

• Mode pins (MD0 to MD2)

Those pins must be directly connected to VCC5 or VSS for use.

Pattern lengths between VCC5 or VSS and each mode pin on the printed-circuit board should be arranged to

be as short as possible to prevent the test mode from being erroneously turned on due to noise, and they

should be connected with low impedance.

• Power pins

When there are a number of VCC5/VCC3/VSS, those whose electrical potential must be the same within the

device are connected to prevent erroneous operation such as latch-up for device design purposes, but those

must be externally connected to a power source and earthed to follow the general output current standard and

prevent erroneous operation of strobe signals due to increased ground level and reduction in unnecessary

radiation.

Care must also be taken to ensure that they are connected to the VCC5/VSS or VCC3/VSS of this device at the

lowest possible impedance from the source of the electrical current supply.

Furthermore, it is recommended that a ceramic capacitor of around 0.1 µF be used to connect the VCC5 and

VSS, or VCC3 and VSS near the device as a bypass capacitor.

• Crystal oscillation circuits

Noise near the X0, X1, X0A or X1A pins can cause erroneous operation. The printed-circuit board must be

designed so that the X0, X1, X0A and X1A pins, crystal oscillator (or ceramic oscillator) and bypass capacitor

to the ground can be arranged as close as possible.

Also, a printed-circuit board with grounded artwork enclosing the X0, X1, X0A and X1A pins is strongly

recommended to ensure stable operation.

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