TVS PRODUCT SELECTOR GUIDE
------SHANGHAI SEMITECH SEMICONDUCTOR CO., LTD.
Feb.
2007
Electrostatic Discharge (ESD) frequently occurs in
nature, as well as inmanufacturing environments and
in-use finished electronic equipment.
ESD is observed to account for close to 10% of all
failures in silicon ICs, and as a consequence, customer
warranty claims.
The discharge occurs at our finger when our body is
electrically charged and is in close proximity of
contact points on electronic devices.
Furthermore, with the added features and integration of
multiple functions, IC designs have become more
sensitive to ESD. This has left designers with the
challenge of providing the most effective ESD protection
to the IC as possible while minimizing board space and
cost for additional protection devices.
Today, our Transient Voltage Suppressors (TVS) and ESD
Protection Arrays are your best solution.
Guide to TVS components selection
1.What is the continuous or repetitive peak voltages at
the circuit location the TVS will be placed to protect a
sensitive load?
NOTE: This will determine “Working Standoff Voltage” or
Vwm found on TVS data sheets. Any of these TVS devices
serve as a clamp and are placed in parallel to the
sensitive load to divert high surge currents to ground
or around the sensitive load.
2.What is the worst-case transient waveform in peak
impulse current and pulse width duration the TVS needs
to divert around the sensitive load?
NOTE: This will determine Peak Impulse Current or Ipp as
well as pulse width to help further select the correct
Part Number(s) on TVS data sheets.
3.What is the worst case peak voltage the sensitive load
can withstand for the pulse duration in item #2 above?
NOTE: This will determine the clamping voltage or Vc
required from the TVS on the data sheets.
4.What is the repetitive peak pulse power dissipation
required to further select the correct part?
NOTE: This will determine the important Ppp rating
provided on TVS data sheets. It is the product of the
peak impulse current and the clamping voltage above or
Ppp = Ipp x Vc at the pulse width in item #2
