FR65E Fujitsu Microelectronics, Inc., FR65E Datasheet - Page 14

• Manufacturer Part Number: FR65E
• Description: 32-bit Microcontroller
• Manufacturer: Fujitsu Microelectronics, Inc.

14
MB91307B
• Preventing Latchup
• Treatment of unused input pins
• Power supply pins
• Crystal oscillators
• Treatment of NC pins
• Mode pins (MD0-MD2)
• Operation at startup
• Base oscillator input at startup
MB91307 Series
HANDLING DEVICES
When CMOS integrated circuit devices are subjected to applied voltages higher than V
(other than medium- and high-withstand voltage pins), or to voltages lower than V
in excess of rated levels are applied between V
latchup condition occurs, supply current can increase dramatically and may destroy semiconductor elements.
In using semiconductor devices, always take sufficient care to avoid exceeding maximum ratings.
If unused input pins are left open, abnormal operation may result. Any unused input pins should be connected
to pull-up or pull-down resistance.
Devices are designed to prevent problems such as latchup when multiple V
providing internal connections between pins having the same potential. However, in order to reduce unwanted
radiation, prevent abnormal operation of strobe signals due to rise in ground level, and to maintain total output
current ratings, all such pins should always be connected externally to power supplies and ground. Also, care
must be given to connecting the V
possible.
In addition, it is recommended that a bypass capacitor of 1.0 F be connected between V
the pins as possible.
Noise in proximity to the X0 and X1 pins can cause abnormal operation in this device. Printed circuit boards
should be designed so that the X0 and X1 pins, and oscillators (or crystal oscillators), as well as bypass capacitors
connected to ground, are placed as close together as possible.
The use of printed circuit board architecture in which the X0 and X1 pins are surrounded by ground contributes
to stable operation and is strongly recommended.
Any pins marked “NC” (not connected) must be left open.
These pins should be used in direct connection to V
erroneously switch into test mode, the printed circuit board design should allow the shortest possible pattern
length between 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.
cc
cc
or V
and V
ss
, and the connection should have as little impedance as possible.
ss
pins of this device to a current source with as little impedance as
cc
and V
cc
ss
, a phenomenon known as latchup can occur. When a
or V
ss
. To prevent noise from causing the device to
cc
and V
ss
, as well as when voltages
ss
cc
supply pins are used, by
at input and output pins
cc
and V
ss
as close to