No. 2A201-519EN*A
66
(2) Necessity of countermeasures against static electricity
CT systems contain various semiconductor devices which are very sensitive to static
electricity.
The following table shows the static electricity levels at which each device is damaged.
Table A.1.2-1
Type of component
Voltage range resulting in
component damage (V)
VMOS
30 to 1,800
MOS FET
100 to 200
GaAs FET
100 to 300
EPROM 100
JFET
140 to 7,000
SAW
150 to 500
OP-AMP
190 to 2,500
CMOS
250 to 3,000
Schottky diodes
300 to 2,500
Film resistors
300 to 3,000
Bipolar transistors
380 to 7,000
ECL
500 to 1,500
SCR
680 to 1,000
Schottky TTL
1,000 to 2,500
The level of static electricity that can cause damage differs depending on the type of
device. Damage may be result from static electricity levels of less than 100 V as shown in
the above table. This system conforms to EMC standards IEC60601-1-2 and therefore is
not damaged due to supplied voltage of 3 kV (contact) or 8 kV (in the air).
If this system is to be used in an atmosphere where static electricity of more than 3 kV is
present, countermeasures against static electricity must include the CT system as well as
the environment in which the CT system is installed as targets.
