MB91154PFV-G Просмотр технического описания (PDF) - Fujitsu

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MB91154PFV-G

32-bit Proprietary Microcontrollers

Fujitsu 

MB91F155/MB91154

s HANDLING DEVICES

1. Preventing Latchup

In CMOS ICs, applying voltage higher than VCC or lower than VSS to input/output pin or applying voltage over

rating across VCC and VSS may cause latchup.

This phenomenon rapidly increases the power supply current, which may result in thermal breakdown of the

device. Make sure to prevent the voltage from exceeding the maximum rating.

2. Treatment of Pins

• Treatment of unused pins

Unused pins left open may cause malfunctions. Make sure to connect them to pull-up or pull-down resistors.

• Treatment of open pins

Be sure to use open pins in open state.

• Treatment of output pins

Shortcircuiting an output pin with the power supply or with another output pin or connecting a large-capacity

load may causes a flow of large current. If this conditions continues for a lengthy period of time, the device

deteriorates. Take great care not to exceed the absolute maximum ratings.

• Mode pins (MD0-MD2)

These pins should be used directly connected to either VCC or VSS. In order to prevent noise from causing

accidental entry into test mode, keep the pattern length as short as possible between each mode pin and VCC

or VSS on the board and connect them with low impedance.

• Power supply pins

When there are several VCC and VSS pins, each of them is equipotentially connected to its counterpart inside

of the device, minimizing the risk of malfunctions such as latch up. To further reduce the risk of malfunctions,

to prevent EMI radiation, to prevent strobe signal malfunction resulting from creeping-up of ground level and

to observe the total output current standard, connect all VCC and VSS pins to the power supply or GND.

It is preferred to connect VCC and VSS of MB91F15∗/MB9115∗ to power supply with minimal impedance possible.

It is also recommended to connect a ceramic capacitor as a bypass capacitor of about 0.1 µF between VCC

and VSS at a position as close as possible to MB91F155/MB91154.

• Crystal oscillator circuit

Noises around X0, X1, X0A, and X1A pins may cause malfunctions of MB91F155/MB91154. In designing the

PC board, layout X0, X1 (X0A, X1A) and crystal oscillator (or ceramic oscillator) and bypass capacitor for

grounding as close as possible.

It is strongly recommended to design PC board so that X0, X1, X0A, and X1A pins are surrounded by grounding

area for stable operation.

The MB91F155 and MB91154 devices do not contain a feedback resistor. To use the clock function, you need

to connect an external resistor.

X0A

X1A

MB91F155/MB91154

3. Precautions

• External Reset Input

It takes at least 5 machine cycle to input “L” level to the RST pin and to ensure inner reset operation properly.

• External Clocks

When using an external clock, normally, a clock of which the phase is opposite to that of X0 must be supplied

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