mb91307r Fujitsu Microelectronics, Inc., mb91307r Datasheet - Page 15

• Manufacturer Part Number: mb91307r
• Description: 32-bit Microcontroller Cmos Fr60 Mb91307 Series
• Manufacturer: Fujitsu Microelectronics, Inc.

• About crystal oscillator circuit
• Treatment of NC pins
• About mode pins (MD0 to MD2)
• Operation at startup
• Base oscillator input at startup
• Caution on Operations during PLL Clock Mode
• Precaution on using ports 6 and 7
• Sample use of Stop Mode with 3.3 V power supply
Noise near the X0 and X1 pins may cause the device to malfunction. Design the printed circuit board so that
X0, X1, the crystal oscillator (or ceramic oscillator) , and the bypass capacitor to ground are located as close to
the device as possible.
It is strongly recommended to design the PC board artwork with the X0 and X1 pins surrounded by ground plane
because stable operation can be expected with such a layout.
Any pins marked “NC” (not connected) must be left open.
Mode pins (MD0 to MD2) should be connected directly to V
To prevent the device erroneously switching to test mode due to noise, design the printed circuit board such that
the distance between the mode pins and V
Immediately after a power-on startup, always apply a reset initialization (INIT) at the INIT pin. Also, in order to
assure a wait period for the oscillator circuits to stabilize immediately after startup, be sure that the “L” level input
to the INIT pin continues for the required stabilization wait interval. (The INIT cycle for the INIT pin includes only
the minimum setting for the stabilization wait period.)
At power-on startup, always input a clock signal until the oscillator stabilization wait period is ended.
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.
If one of P60/A15 to P70/A24, which are shared for output of external bus interface addresses, is used as a port,
a grid voltage is applied to the port instantaneously when the status of another address output pin is changed.
Therefore, add resistors or capacitors to those ports to prevent application of the grid voltage.
2.4 k
7.6 k
3.3 V
GND
CC
or V
SS
0.1 F
is as short as possible and the connection impedance is low.
CC
or V
V
C
V
CC
SS
SS
.
MB91307 Series
15