DS07-16303-3E Datasheet, PDF (14/97 Pages) Fujitsu Component Limited. – 32-bit RISC Microcontroller CMOS FR30 Series

MB91121
s HANDLING DEVICES
• Preventing Latchup
In CMOS ICs, applying voltage higher than VCC or lower than VSS to input/output pin or applying voltage over
rating across VCC and VSS may cause latchup.
This phenomenon rapidly increases the power supply current, which may result in thermal breakdown of the
device. Make sure to prevent the voltage from exceeding the maximum rating.
Take care that the analog power supply (AVCC AVR) and the analog input do not exceed the digital power supply
(VCC) when the analog power supply turned on or off.
• Treatment of Unused Pins
Unused pins left open may cause malfunctions. Make sure to connect them to pull-up or pull-down resistors.
• External Reset Input
It takes at least 5 machine cycle to input “L” level to the RST pin and to ensure inner reset operation properly.
• Remarks for External Clock Operation
When external clock is selected, supply it to X0 pin generally, and simultaneously the opposite phase clock to
X0 must be supplied to X1 pin. However, in this case the stop mode must not be used (because X1 pin stops
at “H” output in stop mode) .
And can be used to supply only to X0 pin with 5 V power supply at 12.5 MHz and less than.
• Using an external clock
X0
X1
MB91121
Using an external clock (normal)
Note: Can not be used stop mode (oscillation stop mode).
OPEN
X0
X1
MB91121
Using an external clock (can be used at 12.5 MHz and less than.)
• Power Supply Pins
When there are several VCC and VSS pins, each of them is equipotentially connected to its counterpart inside of
the device, minimizing the risk of malfunctions such as latch up. To further reduce the risk of malfunctions, to
prevent EMI radiation, to prevent strobe signal malfunction resulting from creeping-up of ground level and to
observe the total output current standard, connect all VCC and VSS pins to the power supply or GND.
It is preferred to connect VCC and VSS of MB91121 to power supply with minimal impedance possible.
It is also recommended to connect a ceramic capacitor as a bypass capacitor of about 0.1 µF between VCC and
VSS at a position as close as possible to MB91121.
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