MB91110 查看數據表（PDF） - Fujitsu

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MB91110

32-Bit RISC Microcontroller

Fujitsu 

MB91110 Series

s HANDLING DEVICES

• Preventing Latch-up

The “Latch-up” phenomenon may be generated if a voltage in excess of VCC or lower than VSS is applied to the

input/output pins, or if the voltage exceeds the rating between VCC and VSS. If latch-up is generated, the electrical

current increases significantly and may destroy certain components due to the excessive heat, so great care

must be taken to ensure that the maximum rating is not exceeded during use.

• Handling Unused Input Pins

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

left open.

• External Reset Input

“L” level should be input to the RST pin, which is required for at least five machine cycles to ensure the internal

status is reset.

• Using External Clocks

If external clock is used, X0 pin should be provided, and X1 pin should be provided with reverse phase to X0

pin input. If the STOP mode (oscillation stop mode) is used simultaneously, the X1 pin is stopped with the “H”

output. So, when STOP mode is specified, approximately 1 kΩ of resistance should be added externally. An

example of the external clock usage methods is shown in the following circuit.

Example of External Clock Usage (normal case)

X0

X1

MB91110

Note : Resistance must be added to the X1 pin if the STOP mode (oscillation stop mode) is used.

• 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 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 current rating.

Make sure to connect Vcc and Vss pins via the lowest impedance to power lines.

It is recommended to provide a bypass capacitor of around 0.1 F between Vcc and Vss pins near the device.

• Crystal Oscillator Circuits

Noise around the X0 or X1 pins may cause erroneous operation. Make sure to provide bypass capacitors via

shortest distances from X0, X1 pins, crystal oscillator (or ceramic resonator) and ground lines, and make sure

that lines of oscillation circuits not cross the lines of other circuit.

A printed circuit board artwork surrounding the X0 and X1 pins with ground area for stabilizing the operation is

highly recommended .

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