MB91107 View Datasheet(PDF) - Fujitsu

Part Name

Description

Manufacturer

MB91107

32-bit RISC Microcontroller

Fujitsu 

MB91107/108

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.

•Handling the output pins

Connecting an output pin to the power supply, to another output pin, or to a large-capacitance load may cause

a large current to flow. Since letting it flow for an extended period of time degrades the device, be careful in

using the device not to exceed the maximum rating.

•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 MB91107 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 MB91107.

•Mode setting pins (MD0 to MD2)

Connect mode setting pins (MD0 to MD2) directly to VCC or VSS.

Arrange each mode setting pin and VCC or VSS patterns on the printed circuit board as close as possible and

make the impedance between them minimal to prevent mistaken entrance to the test mode caused by noises.

•Crystal oscillator circuit

Noises around X0 and X1 pins may cause malfunctions of MB91101. In designing the PC board, layout X0, X1

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 X1 and X0 pins are surrounded by grounding area for

stable operation.

3. Notes on Use

•External reset input

The RST pin requires "L" level input for at least five machine cycles before the the internal circuitry can be

completely reset.

•External clock

To use an external clock, in principle, supply the X0 and X1 pins with a clock signal opposite in phase to the X0.

To use the STOP mode (oscillation stop mode) along with the external clock, in which the X1 pin stops with "H"

output, you should insert an external resistor of about 1 kilohm to prevent a collision between outputs.

Given the next page is an example of using an external clock.

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