What is ESD ?
It is a kind of transient voltage noise. The definition of transient
voltage is listed in IEC 61000-4 series, which describes the
immunity requirements and test methods for electrical and
electric equipments, subjected to ESD, EFT, and surge. Figure 1
is the waveform of ESD, defined in IEC 61000-4-2.
Varistor vs. TVS Diode
ESD current has the rise time of sub-nanosecond, duration of
tens of nanosecond, and its amplitude reaches over 10KV. So,
the protecting device from ESD also needs fast response time.
TVS diode has a similar performance with that of LATTRON's
varistor, in terms of response time and handling capacity. Which,
however, shows inferiority in surge current, leakage current,
operating directionality, polarity, and miniaturization as shown in
the table.
Protection Performance of Lattron is Varistor for ESD
The performance of Lattron is varistor against ESD noise is
tested with the test circuit as shown in Picture 2.
Test procedure includes three different circuit configurations;
without varistor, with varistor at DUT position, and shorted circuit
at DUT position. The test results that had collected with digital
scope are shown in Picture 3.
The performance of ESD suppression with Lattron is varistor is
as good as that of short circuit.
Picture 1.
Picture 2.
Picture 3.
LATTRON®ó VARISTOR
TVS DIODE
Response time
< 1ns
> 1ns
ESD handling
capability
> Contact 8kV, 10 cycle
Leakage current
Low in all spec.
High in case of
low voltage spec.
Surge current
Low especially in
handling capability
High in all spec.
high voltage spec.
Operating temp.
Characteristics are
Characteristics are
deteriorated over 80°C
deteriorated from 25°C
Size
Min. 0603 mm
Min. 1608 mm
TEST INSTRUMENTS : TEKTRONIX TDS3054. MINIZAP
Chip Varistor
APPLICATION FOR ESD
6
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