GUANGDONG ZHAOQING YINGDA INDUCTOR CO。, LTD SMD COMPONENTS
50
Terms and Descriptions
Working DC Voltage (Vw(DC))
This is the maximum continuous DC voltage, which may be applied up to the maximum operating
temperature of the device. The rated DC operating voltage (working voltage) is also used as the
reference point for leakage current. This voltage is always less than the breakdown voltage of the
device.
Working AC Voltage (Vw(AC))
This is the maximum continuous sinusoidal rms voltage, which maybe applied at any temperature up
to the maximum operating temperature of the device.
Maximum Surge Current (Peak Current IP )
This is the maximum peak current, which may be applied for an 8/20µs impulse, with rated line
voltage also applied, without causing device failure. The pulse can be applied to the device in either
polarity with the same confidence factor.
Maximum Surge Energy (Es)
This is the maximum rated transient energy which may be dissipated for a single current pulse at a
specified impulse duration (10/1000µs), with the rated DC or RMS voltage applied, without causing
device failure.
leakage (IL ) at Rated DC Voltage
In the no conducting mode, the device is at a very high impedance (approaching 109ohms) and
appears as an almost open circuit in the system. The leakage current drawn at this level is very low
(<50µA at ambient temperature) and, unlike the zener diode, the multilayer varistors have the added
advantage that, when operated up to its maximum temperature, its leakage current will not increase
above 500µA.
Varistor Voltage (VB(DC))
This is the voltage at which the device changes from the off state to the on state and enters its
conduction mode of operation. The voltage is usually characterized at the 1mA point.
Clamping Voltage (Vc)
This is the peak voltage appearing across the suppressor when measured at conditions of specified
pulse current and specified waveform (8/20µs). It is important to note that the peak current and peak
voltage may not necessarily be coincidental in time.
Capacitance (Cp)
This is the capacitance of the device at a specified frequency 1MHz and bias 0.5V
Application
The Prevention of Overvoltage
When the voltage increases above the threshold of MLV, the suppressor will draws a rapidly
increasing current, and then the overvoltage is considerably attenuated away from the protection of
the equipments should be supplemented by including specific components that will raise the withstand
capabilities to the required level. Varistors provide protection against all kind of overvoltage and
prevent electronic equipment from being damaged by transient events.