Handling Devices - Fujitsu MB89140 Series Hardware Manual

1.6 HANDLING DEVICES

(1) Preventing latch-up
Latch-up may occur if a voltage higher than V
than port 40 to 47, or if voltage exceeding the rated value is applied between V
of up to 7 V can be applied to the P31/INT1 pin irrespective of V
When latch-up occurs, the supply current increases rapidly, sometimes resulting in overheating and destruc-
tion. Therefore, no voltage exceeding the maximum ratings should be used.
(2) Handling unused input pins
Leaving unused input pins open may cause a malfunction. Therefore, these pins should be set to pull-up or
pull-down.
(3) Setting internal connection (IC) pin
Always set IC (internal connections) open.
(4) Variations in supply voltage
Although the specified V
CC
within the specified range may cause a malfunction. Therefore, the voltage supply to the IC should be kept as
constant as possible. The V
10% of the typical V value, or the coefficient of excessive variation should be less than 0.1 V/ms. instanta-
CC
neous change when the power supply is switched.
(5) Precautions for external clocks
It takes some time for oscillation to stabilize after changing the mode to power-on reset (option selection) and
stop. Consequently, an external clock must be input.
(6) Recommended screening conditions
High-temperature aging is recommended for screening before OPTROM-mounted microcontrollers are
mounted.
Program, verify
Writing yield
The test for writing all bits cannot be executed for microcontrollers where the OPTROM microcomputer pro-
gram is not written. Therefore, the 100% writing yield may not be always assured.
(7) Sequence for application of power and analog inputs to A/D converter
Power supplies (AV and AV
CC
after or at the same time the digital power supply (V
When the power supplies is turned off, the digital power supply (V
plies (AV and AV ) and analog inputs (AN0 to ANB) to the A/D converter are turned off.
CC SS
GENERAL
or lower than V
CC
supply voltage operating range is assured, a sudden change in the supply voltage
ripple (P-P value) at the supply frequency (50 to 60 Hz) should be less than
CC
High-temperature aging
150C , 48H
) and analog inputs (AN0 to ANB) to the A/D converter should be turned on
SS
CC
1-16
is applied to the input or output pins other
SS
and V
CC
.
CC
Read
) is turned on.
) should be turned off and the power sup-
CC
. However, voltages
SS
Mount