TRANSIENT VOLTAGE SUPPRESSOR
VRD is a transient voltage
suppressor used for protecting electric
circuits from surge voltage and thus
VRD has superior surge suppression
characteristics, such as extremely fast
response time, very low clamping voltage,
and high surge capacity. Unlike metal oxide
varistors, VRD does not have characteristics
to change with surge variations within the
rated capacity. This feature comprises
another superior characteristics of the VRD
as a transient voltage suppressors.
Figure 1 shows the electrical characteristics. Bipolar
type has almost symmetrical breakdown Voltage (VB)
The reverse breakdown voltage of the ZD type is 200
Volts or more at 10A DC.
VB:Break down voltage
VC:Maximum clamping voltage
IL :Maximum leakage current
IT :Test current
IP :Peak pulse current
One of standard taping is as shown in Figure.
5 or 7
L:26 or 52
Allowable surge capability (Pm) is determined by the
Vc:Maximum clamping voltage
The allowable surge capability (peak pulse power) of
VRD is shown in following Figure 3 and the surge ca-
pability derating characteristics are shown in Figure 6.
ZD, Z1 type
There are many types of surge waveform depending
on the source of the surge. For the VRD surge
suppression characteristics test, the EXP waveform
shown below is used. The EXP waveform is shown as
ta / tb depending on the time width, however 10/1000
waveform is used as the standard test waveform.
Surge suppression characteristics
When EXP waveform is applied to the circuit
below, the surge suppression waveform shown in the
figure 5 can be observed.
IP Peak current
Test pulse waveform
Maximum clamping voltage
clamping voltage waveform
80 100 120 140 160
Ambient temperature (ЊC)