MB90F654A FUJITSU [Fujitsu Component Limited.], MB90F654A Datasheet - Page 18

• Manufacturer Part Number: MB90F654A
• Description: 16-bit Proprietary Microcontroller
• Manufacturer: FUJITSU [Fujitsu Component Limited.]

18
MB90650A Series
8. Initializing
9. Power Supply Pins
10. Crystal Oscillation Circuit
11. About 2 Power Supplies
12. When not Using a Sub Clock Signal
13. Caution on Operations during PLL Clock Mode
In this device there are some kinds of inner resisters which are initialized only by power on reset. It is possible
to initialize these resisters by turning on the power supply again.
When there are several V
within the device when the device is designed in order to prevent misoperation, such as latchup. However, all
of those pins must be connected to the power supply and ground externally in order to reduce unnecessary
emissions, prevent misoperation of strobe signals due to an increase in the ground level, and to observe the
total output current standards.
In addition, give a due consideration to the connection in that current supply be connected to V
the lowest possible impedance.
Finally, it is recommended to connect a capacitor of about 0.1 F between V
bypass capacitor.
Noise in the vicinity of the X0 and X1 pins will cause this device to operate incorrectly. Design the printed circuit
board so that the bypass capacitor connecting X0, X1 and the crystal oscillator (or ceramic oscillator) to ground
is located as close to the device as possible, and that the wiring does not cross the other wirings.
In addition, because printed circuit board artwork in which the area around the X0 and X1 pins is surrounded
by ground provides stable operation, such an arrangement is strongly recommended.
The MB90650A series usually uses the 3-V power supply as the main power source. With Vcc1 = 3 V and Vcc2
= 5 V, however, it can interface with P20/A16 to P27/A23, P30/ALE to P37/CLK, P40/SIN0 to P47, and P70/SDA
to P72 for the 5-V power supply separately from the 3-V power supply at all operation mode. Note, however, that
the analog power supplies such as A/D and D/A can be used only as 3-V power supplies.
Also when the sub-clock is not used, X0A and X1A pins should be connected to an oscillator.
If the PLL clock mode is selected, the microcontroller attempt to be working with the self-oscillating circuit even
when there is no external oscillator or external clock input is stopped. Performance of this operation, however,
cannot be guaranteed.
CC
and V
SS
pins, those pins that should have the same electric potential are connected
CC
and V
SS
near this device as a
CC
and V
SS
with