3
NOTES FOR CMOS DEVICES1 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 devices 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 VDD 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.
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