NOTES FOR CMOS DEVICES
1
PRECAUTION AGAINST ESD FOR SEMICONDUCTORS
Note:
Strong electric field, when exposed to a MOS device, can cause destruction of the
gate oxide and ultimately degrade the device operation. Steps must be taken to stop
generation of static electricity as much as possible, and quickly dissipate it once,
when it has occurred. Environmental control must be adequate. When it is dry,
humidifier should be used. It is recommended to avoid using insulators that easily
build static electricity. Semiconductor devices must be stored and transported in
an anti-static container, static shielding bag or conductive material. All test and
measurement tools including work bench and floor should be grounded. The
operator should be grounded using wrist strap. Semiconductor devices must not
be touched with bare hands. Similar precautions need to be taken for PW boards
with semiconductor devices on it.
2
HANDLING OF UNUSED INPUT PINS FOR CMOS
Note:
No connection for CMOS device inputs can be cause of malfunction. If no
connection is provided to the input pins, it is possible that an internal input level may
be generated due to noise, etc., hence causing malfunction. CMOS device behave
differently than Bipolar or NMOS devices. Input levels of CMOS devices must be
fixed high or low by using a pull-up or pull-down circuitry. Each unused pin should
be connected to V
DD
or GND with a resistor, if it is considered to have a possibility
of being an output pin. All handling related to the unused pins must be judged device
by device and related specifications governing the devices.
3
STATUS BEFORE INITIALIZATION OF MOS DEVICES
Note:
Power-on does not necessarily define initial status of MOS device. Production
process of MOS does not define the initial operation status of the device. Immediately
after the power source is turned ON, the devices with reset function have not yet
been initialized. Hence, power-on does not guarantee out-pin levels, I/O settings
or contents of registers. Device is not initialized until the reset signal is received.
Reset operation must be executed immediately after power-on for devices having
reset function.