MB91107 View Datasheet(PDF) - Fujitsu

Part Name

Description

Manufacturer

MB91107

32-bit RISC Microcontroller

Fujitsu 

MB91107/108

• Notes on using the STOP mode

The regulator built in this product stops in the STOP mode. If the regulator stops due to a malfunction caused

by noise or a fault in the power supply during normal operation, the internal 2.5-V power supply may go below

the lower limit of the guaranteed operating voltage range. When using the STOP mode with the internal regulator,

therefore, be sure to supply an auxiliary external power to prevent the 3.3-V power supply from coming down.

Even in that case, the internal regulator can be restarted by input of a reset signal (To restart the regulator, keep

the reset pin at the L level for at least the oscillation settling time).

•Using STOP mode with 3.3 V power supply

3.3 V

VCC

C

VSS

0.1 µF

2.4 kΩ

7.6 kΩ

5. Turning on the Power Supply

•RST pin

When turning on the power supply, never fail to start from setting the RST pin to “L” level. And after the power

supply voltage goes to VCC level, at least after ensuring the time for 5 machine cycles, then set to “H” level.

•Pin Condition at Turning on the Power Supply

The pin condition at turning on the power supply is unstable. The circuit starts being initialized after turning on

the power supply and then starting oscillation and then the operation of the internal regulator becomes stable.

So it takes about 42 ms for the pin to be initialized from the oscillation starting at the source oscillation 12.5 MHz.

Take care that the pin condition may be output condition at initial unstable condition.

(With the MB91107, however, initalization can be achieved in less than about 42 ms after turning on the internal

power supply by maintaining the RST pin at "L" level.)

•Source Oscillation Input at Turning on the Power Supply

At turning on the power supply, never fail to input the clock before cancellation of the oscillation stabilizing waiting.

•Hardware Stand-by at Turning on the Power Supply

When turning on the power supply with the HST pin being set to “L” level, the hardware doesn’t stand by. However

the HST pin becomes available after the reset cancellation, the HST pin must once be back to “H” level.

•Power on Reset

Make sure to make power on reset at turning on the power supply or returning on the power supply when the

power supply voltage is below the warranty range for normal operation.

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