TVS Datasheet, PDF (1/4 Pages) Vishay Siliconix – Transient Voltage Suppressors (TVS) for Automotive Electronic Protection

VISHAY GENERAL SEMICONDUCTOR
Transient Voltage Suppressors
Application Note
Transient Voltage Suppressors (TVS) for
Automotive Electronic Protection
By Soo Man (Sweetman) Kim,
Senior Application Manager
A major challenge in automotive design is protecting
electronics - such as control units, sensors, and
entertainment systems - against damaging surges, voltage
transients, ESD, and noise that are present on the power
line. Transient voltage suppressors (TVS) are ideal solutions
for automotive electronic protection and have several
important parameters for these applications, including
power rating, stand-off voltage, breakdown voltage, and
maximum breakdown voltage. Following are definitions for
these parameters.
Power rating
The power rating of a TVS is its surge-absorbing capability
under specific test or application conditions. The industrial-
standard test condition of 10 μs/1000 μs pulse form
(Bellcore 1089 spec.), as shown in Figure 1. This test
condition differs from the TVS ESD test condition of
8 μs/20 μs pulse form, as shown in Figure 2.
100 %
10 µs
I_PPM
10 μs/1000 μs
50 %
I_PPM
2
0%
0
0.5
1.0
1.5
2.0
2.5
(ms)
Fig. 1 - Test Waveform of TVS
8 μs
100 %
8 μs/20 μs
I_PPM
50 %
I_PPM
2
0%
0
5
10
15
20
25
(μs)
Fig. 2 - Test Waveform of TVS ESD
Breakdown Voltage (V_BR)
The breakdown voltage is the voltage at which the device
goes into avalanche breakdown, and is measured at a
specified current on the datasheet.
Maximum Breakdown Voltage (V_C: Clamping Voltage)
The clamping voltage appears across the TVS at the
specified peak pulse current rating. The breakdown voltage
of a TVS is measured at a very low current, such as 1 mA
or 10 mA, which is different from the actual avalanche
voltage in application conditions. Thus, semiconductor
manufactures specify the typical or maximum breakdown
voltage in large current.
Stand-Off Voltage (V_WM): Working Stand-Off Reverse
Voltage
The stand-off voltage indicates the maximum voltage of the
TVS when not in breakdown, and is an important parameter
of protection devices in circuits that do not operate under
normal conditions. In automotive applications, some
regulation of the automotive electronics is provided by
“jump-start protection”. This condition supplies 24 V_DC in
10 min to 12 V type electronics, and 36 V_DC in 10 min to
24 V type electronics without damage or malfunction of the
circuit. Thus, the stand-off voltage is one of the key
parameters in TVS for automotive electronics.
Document Number: 88490 For technical questions within your region, please contact one of the following:
Revision: 09-Aug-10
[e-mail], [e-mail], [e-mail]
www.vishay.com
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